| protection against leishmania major infection in genetically susceptible balb/c mice by gp63 delivered orally in attenuated salmonella typhimurium (aroa- arod-). | the gene encoding the leishmania major (l. major) promastigote surface glycoprotein, gp63, was introduced into the salmonella typhimurium (s. typhimurium) aroa- arod- live oral vaccine strain brd509 and expressed under the control of a constitutive tac promoter in plasmid pkk233-2. this construct (gid101) expressed gp63 in vitro and was used to immunize highly susceptible balb/c mice by the oral route. the plasmid was relatively stably inherited by bacteria growing or persisting in the mesenteri ... | 1995 | 7635511 |
| leishmania major: in vitro ultrastructural study of the paraxial rod of promastigotes. | the flagellum of leishmania major promastigotes has an intraflagellar structure known as the paraxial rod (par) which extends from a point halfway in the flagellar pocket to the tip of the flagellum, lying opposite the axonemal microtubule doublets 4-7. an expansion of the axonemal plasma membrane envelops the par and may provide desmosomal attachment at the orifice of the flagellar pocket. the complex organization of the 4-6 nm thick filaments in the par was studied by us in cross, oblique, lon ... | 1995 | 7635620 |
| a member of the clpb family of stress proteins is expressed during heat shock in leishmania spp. | we have identified and isolated the leishmania major homologue to the bacterial clpb gene and to the yeast hsp104 gene. clpb in leishmania major is a single-copy gene and encodes a low-abundance mrna which is induced several-fold during a heat stress. we raised antibodies against the product of the recombinant gene and show that the leishmanial clpb encodes a predominantly cytoplasmic protein of approx. 100 kda which is detectable in leishmania promastigotes of various species after exposure to ... | 1995 | 7637691 |
| high constitutive levels of heat-shock proteins in human-pathogenic parasites of the genus leishmania. | we have analysed the transcription of three heat-shock genes, hsp70, hsp83 and clpb, in the protozoan parasite leishmania. all three heat-shock genes are transcribed constitutively and not heat-inducibly. however, we find that two major heat-shock proteins, hsp70 and hsp83, are synthesized at elevated rates during heat stress. we conclude that the cellular stress response in leishmaniae is regulated exclusively on a post-transcriptional level much in contrast with all other eukaryotes examined s ... | 1995 | 7646449 |
| prediction of omega site in nascent precursor of glycosylphosphatidylinositol protein. | | 1995 | 7651179 |
| microscale analysis of glycosylphosphatidylinositol structures. | | 1995 | 7651181 |
| structure of and kinetic channelling in bifunctional dihydrofolate reductase-thymidylate synthase. | the bifunctional enzyme dihydrofolate reductase-thymidylate synthase catalyses both the reductive methylation of 2'-deoxyuridylate and the subsequent reduction of dihydrofolate to yield 2'-deoxythymidylate and tetrahydrofolate at two spacially discrete sites situated on different protein domains. the x-ray structure of dihydrofolate reductase-thymidylate synthase from leishmania major indicates that transfer of dihydrofolate between these sites does not occur by transient binding at both sites b ... | 1994 | 7656037 |
| characterization of 'old world' leishmania species using amplified minicircle variable regions as molecular probes. | | 1995 | 7660454 |
| amino acid sequence of the ribosomal protein hs23 from the halophilic haloarcula marismortui and homology studies to other ribosomal proteins. | the ribosomal protein hs23 from the 30s subunit of the extreme halophilic haloarcula marismortui, belonging to the group of archaea, was isolated either by rp-hlplc or two-dimensional polyacrylamide gel electrophoresis. the complete amino acid sequence was determined by automated n-terminal microsequencing. the protein consists of 123 residues with a corresponding molecular mass of 12,552 da as determined by electrospray mass spectroscopy; the pi is 11.04. homology studies reveal similarities to ... | 1995 | 7662106 |
| early parasite containment is decisive for resistance to leishmania major infection. | we investigated the early spread of leishmania major in various mouse strains. in balb/c mice, which are extremely vulnerable to l. major infection, the parasites disseminated within 10-24 h from the site of subcutaneous footpad infection in to the popliteal lymph node, spleen, lung, liver and bone marrow. application of recombinant (r)il-12 prior to infection prevented the early dissemination of parasites into visceral organs and the animals healed the infection. in three mouse strains tested, ... | 1995 | 7664785 |
| transgenic mice expressing high levels of soluble tnf-r1 fusion protein are protected from lethal septic shock and cerebral malaria, and are highly sensitive to listeria monocytogenes and leishmania major infections. | mice bearing a transgene coding for a soluble tumor necrosis factor receptor type 1 (tnfr1)-fcigg3 fusion protein and placed under the control of the alpha-1-antitrypsin gene promoter were generated. depending on the mouse line, blood levels of the protein ranged from 25 ng/ml to over 100 micrograms/ml; this level of expression was most often transmitted to the transgene-bearing progeny as a relatively stable feature. high-expressor mice were completely resistant to lipopolysaccharide-induced sh ... | 1995 | 7664802 |
| cultivation of leishmania sp. in nutrient broth. | bone-marrow aspiration and biopsy material samples obtained from two patients, one diagnosed as visceral and other as cutaneous leishmaniasis, were inoculated in novy, mcneal, nicolle (nnn) medium and nutrient broth (nb), containing fetal calf serum (fcs), penicillin and streptomycine. both media were incubated at 27 degrees c for 10 days and observed daily for l. infantum and l. major promastigotes. promastigotes were observed in nutrient broth after the first day, while in nnn media after the ... | 1995 | 7665939 |
| complement-mediated lysis and infectivity for mouse macrophages and sandflies of virulent and attenuated leishmania major promastigotes varying in expression of the major surface protease and lipophosphoglycan. | the infectivity to mouse macrophages and sandflies, the expression and enzymatic activity of the major surface glycoprotein (gp63), the developmental modification of lipophosphoglycan (lpg) and three metacyclogenesis markers (promastigote body size, lectin agglutination and complement resistance) were compared in four related leishmania major promastigote lines. the lines, which differed in their virulence for balb/c mice, were examined in both logarithmic and stationary phase. although the two ... | 1995 | 7668915 |
| phosphorylation of proteins in virulent promastigotes from leishmania major. | protein kinases are present in the plasma membrane of the human parasite leishmania. a marked increase in enzyme activity has been detected as cultures entered into the stationary phase of growth. since avirulent parasites can be separated from virulent forms by the peanut agglutinin (pna), we have examined the change in the protein kinase activity of l. major during growth in vitro and the difference in phosphorylation with virulent promastigotes (pna-) of l. major. marked similarities were fou ... | 1993 | 7670538 |
| crystallization and preliminary x-ray diffraction studies of leishmanolysin, the major surface metalloproteinase from leishmania major. | the membrane-bound gpi-anchored zinc metalloproteinase leishmanolysin purified from leishmania major promastigotes has been crystallized in its mature form. two crystal forms of leishmanolysin have been grown by the vapor diffusion method using 2-methyl-2,4-pentanediol as the precipitant. macroseeding techniques were employed to produce large single crystals. protein microheterogeneity in molecular size and charge was incorporated into both crystal forms. the tetragonal crystal form belongs to t ... | 1995 | 7675788 |
| the complete sequence of leishmania rna virus lrv2-1, a virus of an old world parasite strain. | a complete cdna sequence is reported for lrv2-1, the first leishmania rna virus known to infect an old world parasite, leishmania major. sequence analyses show that lrv2-1 differs significantly from members of the lrv1 genus which infect new world parasites. the data support a view that transmission of lrv is strictly vertical and suggest that lrv predate the divergence of old and new world parasites. as a consequence of this divergence, conserved features can be identified for the first time in ... | 1995 | 7676652 |
| serodiagnosis of cutaneous leishmaniasis in jordan using indirect fluorescent antibody test and the enzyme-linked immunosorbent assay. | the usefulness of ifat and elisa, in the detection of antibodies to cutaneous leishmaniasis (cl) in jordanian cases was studied. serum samples were collected from three groups of confirmed or putative cl patients (n = 100), 132 healthy blood donors, 10 patients with pulmonary tuberculosis (tb), and 16 patients with typhoid fever (tf). antigens for both tests were prepared from promastigotes of a leishmania major isolate. at a serum dilution of respectively 1:16 and 1:100 both ifat and elisa had ... | 1995 | 7676907 |
| a randomized, placebo-controlled trial in tunisia treating cutaneous leishmaniasis with paromomycin ointment. | a randomized, placebo-controlled, double-blind trial was carried out in 1992 in central tunisia to assess the tolerability and efficacy of paromomycin ointment against zoonotic cutaneous leishmaniasis caused by leishmania major. one hundred fifteen patients, 2--60 years of age, with a single lesion of parasitologically confirmed cutaneous leishmaniasis, were included in the trial. the ointment was applied twice a day from day 1 through day 14. clinical and parasitologic evaluations of lesions we ... | 1995 | 7677218 |
| mapping human t cell epitopes in leishmania gp63. identification of cross-reactive and species-specific epitopes. | both a conserved surface metalloprotease of leishmania, gp63 as well as certain gp63-derived peptides, have been shown to have immunoprophylactic potential in mouse models of leishmaniasis. in addition, pbmc from individuals with cutaneous, mucosal, or cured visceral leishmaniasis respond in vitro to both native and rgp63. in this report, we mapped human t cell epitopes within gp63. t cells from leishmaniasis patients responded in vitro to certain peptides of gp63 by proliferation and ifn-gamma ... | 1993 | 7678627 |
| repeated induction of nitric oxide synthase and leishmanicidal activity in murine macrophages. | murine macrophages express high levels of nitric oxide (no) synthase and produce large amounts of no when stimulated with interferon-gamma plus lipopolysaccharide in vitro. the expression of no synthase peaks at 12 h after stimulation and declines rapidly to the background level by 72 h. these macrophages can be repeatedly reactivated to express similar levels of no synthase. the reactivation is not due to newly divided cells since peritoneal macrophages which do not divide in vitro and j774 cel ... | 1993 | 7684689 |
| leishmania major-specific, cd4+, major histocompatibility complex class ii-restricted t cells derived in vitro from lymphoid tissues of naive mice. | several studies indicate that the outcome of experimental murine cutaneous leishmaniasis caused by leishmania major (lm) is determined by immunological events occurring shortly after infection. these events lead to outgrowth of either protective cd4+ t cells in the c57bl/6 mouse, which cures, or exacerbative cells in the balb/c mouse, which succumbs to disease. potential factors influencing the outgrowth of protective or exacerbative t cells include antigen-presenting cells (apc), cytokines, and ... | 1993 | 7686209 |
| pre-exposure of murine macrophages to lipopolysaccharide inhibits the induction of nitric oxide synthase and reduces leishmanicidal activity. | murine macrophages produce nitric oxide (no) from l-arginine on stimulation with lipopolysaccharide (lps), alone or with interferon-gamma (ifn-gamma). the effect of incubation of macrophages with low concentrations of lps on no synthesis on subsequent stimulation was investigated, using a murine macrophage cell line, j774, and peritoneal macrophages from cba mice. cells which had been incubated with lps produced significantly lower amounts of no, and expressed lower levels of no synthase activit ... | 1993 | 7686861 |
| phagocytosis and induction of nitric oxide synthase in murine macrophages. | the murine macrophage cell line, j774, produced little or no detectable levels of nitric oxide (no) when stimulated with interferon-gamma (ifn-gamma) alone in vitro. however, they expressed high levels of no synthase and produced large amounts of no when cultured with ifn-gamma in the presence of lipopolysaccharide (lps). the synergistic action of lps can be replaced by ingestion by the macrophages of zymosan, staphylococcus aureus or leishmania major in a dose-dependent manner. in contrast, the ... | 1993 | 7691724 |
| monoclonal antibodies directed against leishmania secreted acid phosphatase and lipophosphoglycan. partial characterization of private and public epitopes. | leishmania promastigotes, the stage of the parasite characteristic for the sandfly vector, express an abundant glycoconjugate, called lipophosphoglycan, at their surface. lipophosphoglycan consists of lysoalkyl-sn-glycerophosphoinositol linked to a phosphosaccharide core conserved in all species, which is connected to po4-6gal beta 1,4man alpha 1 repeats with species-specific substitutions at the gal residue; the repeats are capped by conserved and species-specific oligosaccharides. most leishma ... | 1993 | 7693464 |
| transfer of cd4+ t cells to c.b-17 scid mice: a model to study th1 and th2 cell differentiation and regulation in vivo. | | 1994 | 7701113 |
| dendritic cells in leishmania major-immune mice harbor persistent parasites and mediate an antigen-specific t cell immune response. | upon infection with leishmania major, a cause of human cutaneous leishmaniasis, mice of resistant strains are able to control the infection, with lesions resolving spontaneously. a long-lasting cell-mediated immunity protects them from reinfection. nevertheless, small numbers of viable parasites persist in the lymph nodes of these mice. we have recently documented that, in addition to macrophages, epidermal langerhans cells can ingest l. major. furthermore, langerhans cells have the unique abili ... | 1995 | 7705398 |
| glycoinositolphospholipids of leishmania major inhibit nitric oxide synthesis and reduce leishmanicidal activity in murine macrophages. | murine macrophages express high levels of inducible nitric oxide (no) synthase and produce large amounts of nitric oxide when activated with interferon-gamma and lipopolysaccharide in vitro. nitric oxide is a mediator of a variety of biological functions including microbicidal activity against the protozoan parasite leishmania species. glycoinositolphospholipids (gipl) are the predominant surface glycolipids in both developmental stages of leishmania major. we report here that gipl can inhibit t ... | 1995 | 7705404 |
| induction of a th2 population from a polarized leishmania-specific th1 population by in vitro culture with il-4. | the infection of mice with leishmania major parasite induces polarized th1 and th2 responses that cannot be significantly changed in vivo after 2 to 3 wk of infection by using either cytokines or anti-cytokine abs. it is not clear, however, whether the t cell populations are irreversibly differentiated or whether the inability to modify the cytokine production reflects inefficiencies in the experimental treatments or complications of the infection itself. to study this further, we have cultured ... | 1995 | 7706719 |
| evaluation of recombinant gp63, the major leishmania surface glycoprotein, as a diagnostic molecule for leishmaniasis in vervet monkeys. | | 1994 | 7709873 |
| transient inducible events in different tissues: in situ studies in the context of the development and expression of the immune responses to intracellular pathogens. | intracellular pathogens whether facultative like mycobacterium sp., e.g. bacillus calmette guérin, listeria monocytogenes or strictly intracellular like leishmania sp. initiate either asymptomatic infectious processes or disease depending both on factors of the host (genetic as well as environmental ones) and the infectious/pathogenic agents. in this contribution, we first summarized informations which justify to develop in situ analysis to decipher the sequential events that result in different ... | 1994 | 7713555 |
| prospects for low dose bcg vaccination against tuberculosis. | efficacious vaccination against fast growing pathogens results in a rapid, secondary immune response on natural infection; this provides protection to the vaccinated individual in the race between developing effective immunity and the rapid multiplication of the pathogen. in certain chronic diseases, due to slow growing pathogens, cell-mediated immunity alone can contain the infection, and yet an antibody response is sometimes induced, at the expense of the cell-mediated response, upon natural i ... | 1994 | 7713569 |
| [the isolation and immunochemical study of leishmania antigens]. | the authors describe a procedure for producing the antigen by using a promastigotic suspension of the high-virulent inoculative strain leishmania major. a leishmania culture medium was improved to enhance the yield of parasites up to 1-3 billion cells in a flask. the grown culture was washed off with isotonic sodium chloride solution, from the medium residues and concentrated up to 1 billion cells per ml of the cvolume. the cell concentrate contained no rabbit blood additive, as evidenced by the ... | 1994 | 7715549 |
| modulation of specific t cell responses by concurrent infection with leishmania major and lp-bm5 murine leukemia viruses. | c57bl/6 mice infected with a murine leukemia virus (mulv) mixture designated lp-bm5 develop an immunodeficiency syndrome termed maids, characterized by a variety of t and b cell abnormalities, including elevated levels of ige, suggesting that il-4 expression is increased in these animals. it has been suggested that the immunodeficiency associated with maids is caused by a conversion of immune responses normally characterized by th1 development towards a th2-dominated response. mice of the same s ... | 1995 | 7718509 |
| conversion of human fibroblasts to tissue macrophages by the snyder-theilen feline sarcoma virus (st:fesv(felv)): productive infection by leishmania major. | the decisive role of macrophages in t-cell differentiation is best exemplified by cutaneous leishmaniasis. during infection, leishmania attach to macrophages, the only site of replication for the parasite. we have recently demonstrated the conversion of human fibroblasts to tissue macrophages (tm) by transduction with the snyder-theilen feline sarcoma virus (st:fesv-(felv)). since leishmania have tropism only for macrophages, we have used the parasite to ascertain the functional phenotype of the ... | 1994 | 7721332 |
| the role of the innate immune response in th1 cell development following leishmania major infection. | infection of mice with the protozoan parasite leishmania major is an established model with which to study the in vivo development of cd4+ th cell subsets. interferon-gamma (ifn-gamma), produced by natural killer (nk) cells (asgm1+, cd4-, cd8-, cd3-), regulates cd4+ t cell subset development and early resistance to l. major. rapid th1 cell development and resistance to infection occur in mice that develop an nk cell response early after infection (c3h and immunized balb/c mice), whereas mice tha ... | 1995 | 7722408 |
| interleukin 12 signaling in t helper type 1 (th1) cells involves tyrosine phosphorylation of signal transducer and activator of transcription (stat)3 and stat4. | interleukin 12 (il-12) initiates the differentiation of naive cd4+ t cells to t helper type 1 (th1) cells critical for resistance to intracellular pathogens such as leishmania major. to explore the basis of il-12 action, we analyzed induction of nuclear factors in th1 cells. il-12 selectively induced nuclear dna-binding complexes that contained stat3 and stat4, recently cloned members of the family of signal transducers and activators of transcription (stats). while stat3 participates in signali ... | 1995 | 7722452 |
| conservation among old world leishmania species of six physical linkage groups defined in leishmania infantum small chromosomes. | we have characterised 49 dna probes specific for each of the six smallest chromosomes in leishmania infantum and have examined the allocation of these probes in the molecular karyotypes of the other old world leishmania species leishmania donovani, leishmania major, leishmania tropica and leishmania aethiopica. these 49 probes define 6 physical linkage groups in the molecular karyotypes of various strains of l. infantum. 40 of these probes hybridise in the other old world leishmania species and ... | 1995 | 7723776 |
| switch from a type 2 to a type 1 t helper cell response and cure of established leishmania major infection in mice is induced by combined therapy with interleukin 12 and pentostam. | successful treatment in allergic, autoimmune, and infectious diseases often requires altering the nature of a detrimental immune response mediated by a particular cd4+ t helper (th) cell subset. while several factors contribute to the development of cd4+ th1 and th2 cells, the requirements for switching an established response are not understood. here we use infection with leishmania major as a model to investigate those requirements. we report that treatment with interleukin 12 (il-12), in comb ... | 1995 | 7724530 |
| expression cloning of a protective leishmania antigen. | parasite-specific cd4+ t cells have been shown to transfer protection against leishmania major in susceptible balb/c mice. an epitope-tagged expression library was used to identify the antigen recognized by a protective cd4+ t cell clone. the expression library allowed recombinant proteins made in bacteria to be captured by macrophages for presentation to t cells restricted to major histocompatibility complex class ii. a conserved 36-kilodalton member of the tryptophan-aspartic acid repeat famil ... | 1995 | 7725103 |
| homology modelling of the dihydrofolate reductase-thymidylate synthase bifunctional enzyme of leishmania major, a potential target for rational drug design in leishmaniasis. | a homology model of the dimeric leishmania major dihydrofolate reductase-thymidylate synthase bifunctional enzyme was built based upon the available crystallographic structures of the dihydrofolate reductase and thymidylate synthase monofunctional enzymes. the corresponding substrates, cofactors and inhibitors of the monofunctional enzymes were modelled in the active-sites of the homodimeric model of the bifunctional enzyme. the small number of residues in the interdomain region of the l. major ... | 1994 | 7727680 |
| il-12 is required for natural killer cell activation and subsequent t helper 1 cell development in experimental leishmaniasis. | infection of mice with the protozoan leishmania major is an established in vivo model for the definition of factors that contribute to cd4+ t helper cell subset development. in the current study, a central role for il-12 in directing both the innate and adaptive immune responses to l. major is established. we show that in vivo neutralization of il-12 eliminates the nk cell cytotoxic response and ifn-gamma production by lymph node cells from 2-day l. major-infected c3h mice. moreover, anti-il-12 ... | 1995 | 7730635 |
| biosynthesis of lipophosphoglycan from leishmania major: characterization of (beta 1-3)-galactosyltransferase(s). | lipophosphoglycan (lpg) is the major cell surface molecule of promastigotes of all leishmania species. it is comprised of three domains: a conserved gpi anchor linked to a repeating phosphorylated disaccharide (p2; po4-6-gal(beta 1-4)man(alpha 1-) backbone variously substituted with galactose, glucose and arabinose residues in l.major and capped with a neutral oligosaccharide. using a microsomal membrane preparation from l.major, we have been able to demonstrate that galactose from udp-[14c]gala ... | 1994 | 7734847 |
| the gene encoding streptothricin acetyltransferase (sat) as a selectable marker for leishmania expression vectors. | the plex series of vectors was developed for the stable expression of exogenous genes in the protozoan parasite leishmania. these puc-based constructs contain one of three independent selectable markers and a multiple cloning site inserted between the upstream and downstream untranslated regions of the previously cloned leishmania major hexbp gene. selection was based on resistance to the aminoglycosides, hygromycin b and neomycin, and to nourseothricin, a novel independent selectable marker for ... | 1995 | 7737509 |
| regulation of nitric oxide synthesis in infectious and autoimmune diseases. | nitric oxide (no) is an essential mediator for a variety of biological functions, including defence against a range of pathogens. however, excessive production of no as a result of immunological stimulation, will lead to important immunopathologies. therefore the production of no is necessarily under tight regulation. the regulatory mechanisms so far known to control no synthesis include cytokines (induction of no synthase by ifn-gamma, tnf alpha, mif and lps, and down regulation by il-4, il-10 ... | 1994 | 7737695 |
| dichotomy of the t cell response to leishmania antigens in patients suffering from cutaneous leishmaniasis; absence or scarcity of th1 activity is associated with severe infections. | the t cell response was studied in 25 patients suffering from cutaneous leishmaniasis caused by leishmania major with severe (n = 10) and mild (n = 15) disease manifestations. peripheral blood mononuclear cells (pbmc) from the patients were activated by sonicates of leishmania promastigotes (lmp) and amastigotes (lda), and the surface protease gp63. the proliferative responses to leishmania antigens were lower in patients with severe disease than in patients with mild disease (p = 0.01-0.05), an ... | 1995 | 7743662 |
| mastomys natalensis and tatera gambiana as probable reservoirs of human cutaneous leishmaniasis in nigeria. | leishmania sp. was isolated from the livers and spleens of 4 of 56 mastomys natalensis and one of 21 tatera gambiana in keana district, nigeria; none of the rodents had cutaneous lesions. parasites were not found in 42 rattus rattus. experimentally infected mice developed cutaneous lesions characteristic of l. major infection. the organisms could not be cultivated in vitro. | 1995 | 7747299 |
| protection against leishmaniasis by injection of dna encoding a major surface glycoprotein, gp63, of l. major. | cdna encoding the highly conserved major surface glycoprotein, gp63, of leishmania major was cloned, together with a signal sequence, into an eukaryotic expression vector, pcdnai, which carries the human cytomegalovirus (cmv) promoter. this construct, pcmv/glycoprotein 63 (gp63), when injected into the skeletal muscle of balb/c mice expressed sustained levels of gp63 in the muscle tissue for at least 40 days. spleen and lymph node cells from the immunized mice produced significant amounts of int ... | 1995 | 7750991 |
| stimulation of b-cell lymphopoiesis by interleukin-7 leads to aggravation of murine leishmaniasis. | the effect of recombinant interleukin-7 (il-7) on the clinical course of murine leishmaniasis and the development of the accompanying immune response was investigated. previously, il-7 has been shown to possess stimulatory capacity for different cell types of the immune and haematopoietic system critically involved in the defence against leishmania major (l. major), such as macrophages which are activated for the elimination of the parasite by il-7. in contrast to these in vitro data, the presen ... | 1995 | 7751025 |
| class ii major histocompatibility complex-deficient mice initially control an infection with leishmania major but succumb to the disease. | class ii major histocompatibility complex (mhc)-deficient (h-2b) mice do not express i-a or i-e molecules and, as a result, do not develop cd4 cells. thus, they represent the ideal model for examining the importance of cd4 cells and mhc class ii molecules in resistance to infection with leishmania major and the capacity of mhc class i-restricted t cells to mediate resistance to l. major. class ii mhc-deficient mice and control (c57bl/6, normal and nude) mice were infected with l. major. although ... | 1995 | 7751707 |
| soluble il-4 receptor, potential for therapeutic and prophylactic intervention. | many bacterial, protozoal and viral infections trigger a cell-mediated immune response. of special importance for the clinical outcome of disease, however, is the relative predominance of t helper (th) cell populations (th1 and th2) secreting different patterns of lymphokines. preferential development of one th subset occurs apparent at the early stages of an infection, suggesting that the mechanisms driving the immune response in one direction or the other operate soon after exposure to the ant ... | 1994 | 7755507 |
| biosynthesis of the glycolipid anchor of lipophosphoglycan and the structurally related glycoinositolphospholipids from leishmania major. | the major macromolecule on the surface of the protozoan parasite leishmania major is a lipophosphoglycan (lpg) which contains a glycosylphosphatidylinositol glycolipid anchor. this parasite also synthesizes a complex family of abundant low-molecular-mass glycoinositolphospholipids (gipls) which are structurally related to the lpg anchor. in this study, l. major promastigotes were metabolically labelled with [3h]glcn, and the kinetics of incorporation into free glycolipids and the lpg anchor foll ... | 1995 | 7755587 |
| diffusely disseminated cutaneous leishmania major infection in a child with acquired immunodeficiency syndrome. | | 1995 | 7761198 |
| infection of human and murine macrophages with leishmania major is associated with early parasite heat shock protein synthesis but fails to induce a host cell stress response. | heat shock/stress proteins (hsp) represent the most conserved proteins expressed in prokaryotes and eukaryotes. these constitutive and inducible proteins function as molecular chaperones and are part of virulence factors. they participate in self/non-self discrimination and may protect phagocytes from the toxic effects of the reactive oxygen species generated by these cells during bacterial phagocytosis and infection. in this study, we investigated the early stress response of host cells [either ... | 1995 | 7768547 |
| effect of iron chelation on the in-vitro growth of leishmania promastigotes. | the development of vaccines and drugs to control leishmaniasis is urgently needed. the presence of a leishmania transferrin receptor on the parasite suggests that an adequate supply of iron is needed for the life cycle of leishmania. we have investigated the effect of iron deprivation on the growth of leishmania promastigotes in vitro using an iron chelation approach. all chelators tested reduced the rate of promastigote multiplication in a dose-dependent fashion, whereas referrated ones did not ... | 1995 | 7768775 |
| [a comparison of the growth of leishmania major, l. turanica and l. gerbilli on nnn medium]. | leishmania promastigotes grew in the nnn medium with medium-199 as a liquid phase. the nnn medium was prepared with agar bases of the following firms: sigma, oxoid, difco, medbioprom (russia). growth characteristics were examined with the following indices: specific growth rate (r), reduplication time (t), reproductive rate (k). the investigations have shown that the kind of agar base has the most influence on the r and t of l.turanica and l.gerbelli and on the k of l.major. the greatest differe ... | 1995 | 7770011 |
| the pathology of cutaneous leishmaniasis due to leishmania major in sudan. | the pathology of cutaneous leishmaniasis in sudan, where the disease is caused by leishmania major, was studied by light and electron microscopy. lesions were classified into four distinct groups based on the ratio of different cell types, especially lymphocytes, macrophages, and plasma cells in the inflammatory infiltrate, and the formation of compact epithelioid granulomas or the presence of necrosis. in the lesions, there was a positive correlation between the number of lymphocytes and the nu ... | 1995 | 7771611 |
| response of scid mice to establishment of leishmania major infection. | the initiation of leishmania major infection in susceptible balb/c mice is regulated by interferon-gamma (ifn-gamma). to examine further the mechanisms of ifn-gamma-dependent regulation of the establishment of l. major, we studied the characteristics of the infection in severe combined immunodeficient (scid) mice. in the first 2 weeks of infection, we observed a delay in the development of the lesions in the footpads and lower numbers of parasites in scid compared with balb/c mice. by week 5 aft ... | 1995 | 7774053 |
| cultivation of leishmania braziliensis in an economical serum-free medium containing human urine. | leishmania braziliensis cells are difficult to culture in vitro and usually require media supplemented with serum for sustained cell division. fresh, sterile urine is an inexpensive substitute for serum in the culture of 2 strains of l. braziliensis, 1 infected with leishmania rna virus 1, and 1 uninfected. in the presence of urine, both the infected and the uninfected strains grew to the same final cell density as the same strains grown in the presence of serum. one strain of leishmania major w ... | 1994 | 7799145 |
| antibodies to leishmania (l) glycolipids and gangliosides in sera of patients with visceral or with zoonotic l. major leishmaniasis. | | 1993 | 7802494 |
| the squash blot technique and the detection of leishmania major in phlebotomus papatasi in tunisia. | this study describes the preliminary applications of the squash blot technique in tunisia, to detect leishmania major in naturally infected phlebotomus papatasi. 309 p. papatasi among 364 female sandflies squashed on to nylon gene screen dna transfer membranes, were identified using the 3.2 kb ribosomal p. papatasi specific dna probe described by ready et al. a second hybridization using the taq1 dna probe described by smith et al. (1989) allowed the detection and identification of the parasite ... | 1993 | 7802506 |
| lipophosphoglycan blocks attachment of leishmania major amastigotes to macrophages. | promastigotes of the intracellular protozoan parasite leishmania major invade mononuclear phagocytes by a direct interaction between the cell surface lipophosphoglycan found on all leishmania species and macrophage receptors. this interaction is mediated by phosphoglycan repeats containing oligomers of beta (1-3)gal residues specific to l. major. we show here that although amastigotes also use lipophosphoglycan to bind to both primary macrophages and a cell line, this interaction is independent ... | 1995 | 7806383 |
| interleukin 12 is effective treatment for an established systemic intracellular infection: experimental visceral leishmaniasis. | when administered at or near the initiation of experimental intracellular infection caused by leishmania major, toxoplasma gondii, or cryptococcus neoformans, treatment with the immuno-regulatory cytokine interleukin 12 (il-12), induces protective antimicrobial activity. in contrast, once infections are established, il-12 exerts considerably less or no effect in the face of a suppressive th2 cell-associated response (l. major) or rapidly progressive fatal infection (t. gondii). to test the effic ... | 1995 | 7807019 |
| epitope mapping of monoclonal antibodies directed against lipophosphoglycan of leishmania major promastigotes. | monoclonal antibodies (mabs) were generated against leishmania major promastigote lipophosphoglycan (lpg) to use as tools in defining functional epitopes of this major cell surface glycoconjugate. epitope mapping of four mabs, designated 4a2-a2, 2g11-a3, 5e6-d10 and 5e10-f2, revealed that the phosphorylated oligosaccharide repeat unit po4-6[gal(beta 1-3)]gal(beta 1-4)man alpha 1-, p3, is a highly immunogenic epitope which has previously been demonstrated, by chemical analyses, to be a repeat uni ... | 1994 | 7808469 |
| recognition of the major cell surface glycoconjugates of leishmania parasites by the human serum mannan-binding protein. | activation of complement on the surface of parasitic protozoa of the genus leishmania appears to be important for parasite infectivity in the mammalian host, as it allows these parasites to attach to and invade macrophages via their surface complement receptors. serum mannan-binding protein (mbp) is a known activator of complement. therefore, in the present study, we have investigated whether serum mbp binds to live leishmania parasites, and to mannose-containing saccharides derived from the par ... | 1994 | 7808481 |
| interferon gamma-independent effects of interleukin 12 administered during acute or established infection due to leishmania major. | interleukin 12 (il-12) is a powerful stimulus for the growth of activated t and natural killer cells, their generation of interferon gamma (ifn-gamma), and the differentiation of t helper type 1 (th1) effector cells from naive precursors in vitro. these activities are consistent with the capacity of exogenous il-12 to heal otherwise susceptible balb/c mice infected with the intramacrophage parasite leishmania major. using this characterized model of cd4 cell subset differentiation, we examined t ... | 1994 | 7809149 |
| cytotoxic and antiparasitic activity from annona senegalensis seeds. | several extracts of annona senegalensis (annonaceae) seeds were tested for antiparasitic activity against leishmania major, leishmania donovani, trypanosoma brucei brucei, and for cytotoxic activity against kb and vero cell lines. fractionation of seeds extracts was mainly guided by means of a biocidal assay against artemia salina nauplii. the biological activities resulted from extract-isolated acetogenins. | 1994 | 7809207 |
| the polymerase chain reaction can reveal the occurrence of naturally mixed infections with leishmania parasites. | on isolation and characterization of leishmania parasites from sudanese patients with visceral leishmaniasis (vl), four cases of mixed infections were found. three of those cases were from the eastern sudan focus of vl. in one case the patient was found to be concomitantly infected with leishmania donovani and leishmania aethiopica, while the remaining three patients possessed mixed infections of leishmania donovani and leishmania major. mixed infections were identified by pcr amplification of l ... | 1994 | 7810388 |
| leishmania major-like parasite, a pathogenic agent of cutaneous leishmaniasis in paraguay. | leishmania parasites isolated from two patients with cutaneous leishmaniasis from geographically different localities in paraguay have been characterized by enzyme electrophoresis (zymodeme) and digestion profiles of kinetoplast dna with restriction enzymes (schizodeme). both paraguayan isolates showed identical zymodeme profiles to each other using 14 enzymes (glutamic pyruvate transaminase, glutamic oxaloacetic transaminase, enolase, fumarate hydratase, glucose phosphate isomerase, glucose-6-p ... | 1994 | 7810807 |
| reduced longevity and fecundity in leishmania-infected sand flies. | phlebotomus papatasi and p. langeroni were infected with leishmania major and l. infantum by membrane feeding. each sand fly ingested approximately 200 parasites per blood meal. higher mortality in both sand fly species was seen with mixed infections than with a single parasite species. there was no significant difference between infections with either l. major or l. infantum in their natural vectors or experimental hosts. infection significantly depressed the mean number of eggs laid per female ... | 1994 | 7810809 |
| endemic kala-azar in eastern sudan: a longitudinal study on the incidence of clinical and subclinical infection and post-kala-azar dermal leishmaniasis. | between april 1991 and april 1993, a longitudinal study was performed in the village of um-salala (1,430 inhabitants) in the endemic area of kala-azar (visceral leishmaniasis) in eastern sudan. during the two years, a total of 92 kala-azar cases were diagnosed (male:female ratio = 1.8:1, mean age 6.6 years). the annual incidence rates were 38.4/1,000 and 38.5/1,000 person-years, respectively. the ratio of clinical to subclinical cases was 1.6:1 in the first year and 2.4:1 in the second year. pos ... | 1994 | 7810819 |
| antiprotozoal activities of benzimidazoles and correlations with beta-tubulin sequence. | benzimidazoles have been widely used since the 1960s as anthelmintic agents in veterinary and human medicine and as antifungal agents in agriculture. more recently, selected benzimidazole derivatives were shown to be active in vitro against two protozoan parasites, trichomonas vaginalis and giardia lamblia, and clinical studies with aids patients have suggested that microsporidia are susceptible as well. here, we first present in vitro susceptibility data for t. vaginalis and g. lamblia using an ... | 1994 | 7811023 |
| identification of an immunodominant 32-kilodalton membrane protein of leishmania donovani infantum promastigotes suitable for specific diagnosis of mediterranean visceral leishmaniasis. | sera from 35 patients suffering from mediterranean visceral leishmaniasis (caused by leishmania donovani infantum) and 59 patients with various forms of cutaneous leishmaniasis prevalent in the sub-mediterranean countries (caused by leishmania major, l. donovani infantum, or leishmania tropica) were tested by immunoblotting and enzyme-linked immunosorbent assay (elisa) with both membrane and soluble antigens prepared from l. donovani infantum parasites. control sera were from healthy children (n ... | 1994 | 7814485 |
| the hsp83 intergenic region in leishmania: conservation of sequence and function across two species. | | 1995 | 7821406 |
| intravenous injection of irradiated leishmania major into susceptible balb/c mice: immunization or protective tolerance. | it is well established that balb/c mice can be protected from fatal infection with leishmania major by prophylactic intravenous (i.v.) immunization with irradiated parasites. protection is critically dependent on the route of injection with i.v. injection being protective and subcutaneous injection not protective. we used this balb/c-l. major model system to investigate this phenomenon. we analyzed quantitatively the parasite-specific, cd4+ t cell mediated immune responses by limiting dilution. ... | 1994 | 7826944 |
| cutaneous leishmaniasis in kenya: sergentomyia garnhami (diptera psychodidae), a possible vector of leishmania major in kitui district: a new focus of the disease. | investigations on phlebotomine sandflies in tseikuru, kitui district, kenya were carried out to determine the vectors of leishmania major. sandflies were trapped from animal burrows over a period of one year using castor oil-smeared sticky traps. nineteen phlebotomine sandfly species were identified and their prevalence in this habitat determined. dissections on the parous sandflies resulted in the isolation of leishmania parasites from phlebotomus martini and sergentomyia garnhami. the isolated ... | 1994 | 7828493 |
| experimental infection of domestic goats with leishmania major through bites of infected phlebotomus duboscqi and needle inoculation of culture-derived promastigotes. | | 1994 | 7831760 |
| trypanosomatid cysteine protease activity may be enhanced by a kininogen-like moiety from host serum. | african trypanosomes contain cysteine proteases (trypanopains) the activity of which can be measured by in vitro digestion of fibrinogen, after electrophoresis in fibrinogen-containing sds/polyacrylamide gels. when assessed by this procedure, trypanopain from trypanosoma brucei (trypanopain-tb) is estimated to have a molecular mass of 28 kda. however, two additional bands of trypanopain activity (87 kda and 105 kda) are observed if serum is added to the trypanopain before electrophoresis. format ... | 1995 | 7832773 |
| t cell genetic background determines default t helper phenotype development in vitro. | a host's ability to resist certain pathogens such as leishmania major can depend upon the phenotype of t helper (th) subset that develops. different murine genetic backgrounds are known to significantly alter the direction of th subset development, although the cellular basis of this influence is poorly understood. to examine the basis of this effect we used an in vitro alpha/beta-t cell receptor (tcr) transgenic system for analysis of th phenotype development. to control for tcr usage, we deriv ... | 1995 | 7836924 |
| characterization of a polymorphic family of integral membrane proteins in promastigotes of different leishmania species. | antibodies raised against a leishmania major recombinant promastigote surface antigen 2 (psa-2) fragment recognized three major polypeptides of approximate m(r) 96,000, 80,000 and 50,000 in promastigotes of three israeli isolates of l. major including the cloned line lrc-l137-v121, but detected a different array of polypeptides in other l. major isolates. the pattern was different both in number of polypeptides detected and their molecular weight. the antibodies to l. major psa-2 also recognized ... | 1994 | 7838170 |
| leishmania resistant to sodium stibogluconate: drug-associated macrophage-dependent killing. | a total of 17 leishmania isolates, 6 of them isolated from antimony-resistant patients, were collected in the sudan and tested for their sensitivity to sodium stibogluconate (pentostam) as promastigotes. six of those isolates were tested as amastigotes infecting a murine macrophage cell line. the results indicated that the conventional promastigote screening assay did not correlate with the clinical picture, whereas the amastigote/macrophage system produced results that pertained to the in vivo ... | 1994 | 7855121 |
| the effect of treating with anti-interleukin-1 receptor antibody on the course of experimental murine cutaneous leishmaniasis. | to assess the role of interleukin-1 (il-1) in cutaneous leishmaniasis, leishmania major-infected mice were treated with an anti-il-1 receptor monoclonal antibody, la-15.6. moab la-15.6 prevents binding of il-1 to both the t cell and b cell/macrophage forms of the il-1 receptor. we found that treating with la 15.6 inhibited the development of cutaneous lesions of l. major in both genetically-susceptible and resistant mice. interestingly, this treatment had little or no effect on parasite numbers ... | 1994 | 7862463 |
| antigen presentation by epidermal langerhans cells in experimental cutaneous leishmaniasis. | cutaneous leishmaniasis is a disease induced by intradermal injection of leishmania promastigotes. since the first cells the parasite encounters are those of the skin, the involvement of this organ in the early immune response might be relevant to the outcome of the disease. in this study we examined the ability of epidermal langerhans cells (lc) to become infected in vivo and to function as antigen presenting cells during the early hours of infection with leishmania major. our experiments showe ... | 1994 | 7862465 |
| t cell and non-t cell compartments can independently determine resistance to leishmania major. | in experimental murine cutaneous leishmaniasis caused by leishmania major (lm), the cellular determinants governing development of protective or exacerbative t cells are not well understood. we, therefore, attempted to determine the influence of t cell and non-t cell compartments on disease outcome. to this end, t cell chimeric mice were constructed using adult thymectomized lethally irradiated, bone marrow-reconstituted (atxbm) animals of genetically resistant, c57bl/6, or susceptible, balb/c, ... | 1995 | 7869047 |
| mice from a genetically resistant background lacking the interferon gamma receptor are susceptible to infection with leishmania major but mount a polarized t helper cell 1-type cd4+ t cell response. | mice with homologous disruption of the gene coding for the ligand-binding chain of the interferon (ifn) gamma receptor and derived from a strain genetically resistant to infection with leishmania major have been used to study further the role of this cytokine in the differentiation of functional cd4+ t cell subsets in vivo and resistance to infection. wild-type 129/sv/ev mice are resistant to infection with this parasite, developing only small lesions, which resolve spontaneously within 6 wk. in ... | 1995 | 7869054 |
| aerobic and anaerobic glucose metabolism of phytomonas sp. isolated from euphorbia characias. | metabolic studies on phytomonas sp. isolated from the lactiferous tubes of the latex-bearing spurge euphorbia characias indicate that glucose is the preferred energy and carbon substrate during logarithmic growth. in stationary phase cells glucose consumption was dramatically reduced. glucose consumption and end-product formation were measured on logarithmically growing cells, both under aerobic (air and 95% o2/5% co2) and anaerobic (95% n2/5% co2 and 100% n2) conditions. the rate of glucose con ... | 1994 | 7870136 |
| in vitro secretion of cytokines by human mononuclear cells of individuals during and after cutaneous leishmaniasis infection. | human peripheral blood mononuclear cells were incubated in the presence of leishmania major promastigotes. the culture supernatants were collected after 24 and 72 h and the cytokine content was measured. it was found that mononuclear cells from cured individuals, in the presence of l. major promastigotes, had increased leishmanicidal activity and secreted increased levels of interferon gamma (ifn gamma), interleukin-2 (il-2) and tumour necrosis factor alpha (tnf). the levels of il-6, on the othe ... | 1993 | 7877848 |
| genetic vaccination against leishmaniasis. | the gene encoding for a major surface glycoprotein, gp63, of leishmania major was cloned into the eukaryotic expression plasmid pcdnai with cmv or rsv promoters. the highly susceptible balb/c mice were injected intramuscularly with 100 micrograms/mouse of the purified plasmid. the plasmids were found to be stable in vivo for at least 40 days after injection and expressed significant levels of gp63, demonstrable by immunohistological staining with specific antibody. the immunized mice developed s ... | 1994 | 7879420 |
| antigen-presenting cells in human cutaneous leishmaniasis due to leishmania major. | in this study biopsies from skin lesions and draining lymph nodes of patients suffering from cutaneous leishmaniasis caused by leishmania major were examined by immunohistochemistry, and by light and electron microscopy to identify the types of antigen-presenting cells (apc) and their location. apc, identified morphologically and by their expression of specific cell markers, included langerhans cells, macrophages, follicular dendritic cells, and interdigitating reticulum cells of the paracortex ... | 1995 | 7882568 |
| changing patterns of cutaneous leishmaniasis in israel and neighbouring territories. | the most frequent form of cutaneous leishmaniasis (cl) in israel and the neighbouring territories is due to leishmania major, which is endemic mainly in the jordan valley and in the rift valley. cl due to l. tropica is much less common, and in the past only sporadic cases have been reported. in this study we present data obtained during the years 1988-1992 regarding cl in the area. our clinic has diagnosed a total of 371 leishmaniasis cases, most of whom acquired the infection in the jordan vall ... | 1994 | 7886757 |
| bicarbonate ions and ph regulation of leishmania major promastigotes. | leishmania major promastigotes are parasites endowed with a plasma membrane electrogenic h+ pump and anionic channels. these systems have been thought to contribute to ph homeostasis of parasites and environmental adaptation by mediating extrusion of protons which are either generated metabolically or result from exogenous acid loads. in this work we show that hco-3 transport plays a physiological role in supporting ph regulation of parasites. intracellular ph (phi) and the membrane potential (v ... | 1995 | 7890030 |
| chloride conductive pathways which support electrogenic h+ pumping by leishmania major promastigotes. | the proton extrusion mechanisms of leishmania promastigotes were studied in terms of electrogenic movements of protons and anions (cl- and hco3-). changes in membrane potential (vm) and intracellular ph (phi) were monitored fluorimetrically with the potential sensitive dye bis-oxonol and the ph-sensitive dye tetraacethoxymethyl 2',7'-bis-(carboxyethyl)-5,6-carboxyfluorescein, respectively. in nominal bicarbonate-free medium (phe 7.4, 28 degrees c), vm and phi of leishmania promastigotes were mai ... | 1995 | 7890641 |
| the pgpa gene of leishmania major mediates antimony (sbiii) resistance by decreasing influx and not by increasing efflux. | | 1994 | 7891738 |
| inverted repeat structure and homologous sequences in the ld1 amplicons of leishmania spp. | in the parasitic trypanosomatids of the genus leishmania, novel circular (cd) and linear (ld) multicopy genetic elements arise de novo either spontaneously or as a result of drug selection. we report that the ld1 minichromosomes of l. donovani, l. major and l. mexicana (ranging in size from 180 to 230 kb) have an inverted repeat structure and contain homologous sequences located at similar distances from the telomere; one half of the chromosome being the mirror image of the other. they must ther ... | 1994 | 7891749 |
| rodents as reservoir hosts of cutaneous leishmaniasis in jordan. | rodents were collected from endemic foci of cutaneous leishmaniasis in jordan, either by flooding their burrows with water or using sherman traps. of the 170 jirds (psammomys obesus) collected, 39 (23%) had leishmania amastigotes in one or both ears. although cultures of ear biopsies from the infected animals were all positive, cultures made using biopsies from their noses, livers or spleens were all negative. the infected jirds were encountered in seven of the nine areas studied. biochemical ch ... | 1994 | 7893175 |
| interleukin-4 and interferon-gamma production by leishmania stimulated peripheral blood mononuclear cells from nonexposed individuals. | interferon-gamma (ifn-gamma) and interleukin-4 (il-4) production by leishmania reactive peripheral blood mononuclear cells (pbmc) from non-exposed individuals was investigated. ifn-gamma was measured in culture supernatants after antigen stimulation. for the measurement of il-4, antigen stimulated cells were pulsed with pma and ionomycin before il-4 release was measured. l. donovani and l. major antigens induced il-4 production (105-1748 pg/ml) in 13 and seven cultures, and ifn-gamma production ... | 1995 | 7899822 |
| course of leishmania infection in beta 2-microglobulin-deficient mice. | mice homozygous for a beta 2-microglobulin (beta 2-m) gene disruption lack the beta 2-m protein and are deficient in functional major histocompatibility complex class i (mhc i) molecules. the mutant mice have normal numbers of cd4+8- t helper cells but lack mhc i-directed cd4-8+ alpha/beta t cells. the beta 2-m mutant and wild-type mice were infected with leishmania major or l. mexicana, which cause cutaneous leishmaniasis in the old and new world, respectively. in both mutant and wild-type mice ... | 1993 | 7901152 |
| an avirulent lipophosphoglycan-deficient leishmania major clone induces cd4+ t cells which protect susceptible balb/c mice against infection with virulent l. major. | an avirulent clone of leishmania major was used to immunize susceptible balb/c mice against challenge with virulent l. major. by using the immunized animals as a source of cells, cd4+ parasite-specific t-cell lines could be generated in vitro which, when adoptively transferred to naive balb/c recipients, conferred marked protection against challenge with virulent l. major. compared with cd4+ parasite-specific t-cell lines generated from nonimmunized balb/c mice infected with l. major, the protec ... | 1993 | 7901166 |
| the adjuvant effect of interleukin-12 in a vaccine against leishmania major. | protection induced by vaccination depends on the capacity of the vaccine to elicit an appropriate immune response. in leishmaniasis, protection requires leishmanial-specific cd4+ t helper (th) cells. vaccination of balb/c mice with leishmanial antigens and interleukin-12 (il-12) promoted the development of leishmanial-specific cd4+ th1 cells. these mice were resistant to subsequent infection with leishmania major. thus, il-12 is an effective adjuvant for the initiation of protective cell-mediate ... | 1994 | 7904381 |
| leishmania promastigotes evade interleukin 12 (il-12) induction by macrophages and stimulate a broad range of cytokines from cd4+ t cells during initiation of infection. | leishmania major are intramacrophage parasites whose eradication requires the induction of t helper 1 (th1) effector cells capable of activating macrophages to a microbicidal state. interleukin 12 (il-12) has been recently identified as a macrophage-derived cytokine capable of mediating th1 effector cell development, and of markedly enhancing interferon gamma (ifn-gamma) production by t cells and natural killer cells. infection of macrophages in vitro by promastigotes of l. major caused no induc ... | 1994 | 7905017 |
| regulatory interactions between cd45rbhigh and cd45rblow cd4+ t cells are important for the balance between protective and pathogenic cell-mediated immunity. | balb/c mice infected with the intracellular protozoan leishmania major mount a t helper cell 2 (th2) response that fails to control growth of the parasite and results in the development of visceral leishmaniasis. separation of cd4+ t cells into cd45rbhigh and cd45rblow subsets showed that the l. major-specific th2 cells were contained within the cd45rblow population as these cells produced high levels of antigen-specific interleukin 4 (il-4) in vitro and transferred a nonhealing response to l. m ... | 1994 | 7905019 |