concanavalin-a and Trypanosomiasis--African

African sleeping sickness is caused by Trypanosoma brucei, a parasite transmitted by the bite of a tsetse fly. Trypanosome infection induces a severe transcriptional downregulation of tsetse genes encoding for salivary proteins, which reduces its anti-hemostatic and anti-clotting properties. To better understand trypanosome transmission and the possible role of glycans in insect bloodfeeding, we characterized the N-glycome of tsetse saliva glycoproteins. Tsetse salivary N-glycans were enzymatically released, tagged with either 2-aminobenzamide (2-AB) or procainamide, and analyzed by HILIC-UHPLC-FLR coupled online with positive-ion ESI-LC-MS/MS. We found that the N-glycan profiles of T. brucei-infected and naïve tsetse salivary glycoproteins are almost identical, consisting mainly (>50%) of highly processed Man3GlcNAc2 in addition to several other paucimannose, high mannose, and few hybrid-type N-glycans. In overlay assays, these sugars were differentially recognized by the mannose receptor and DC-SIGN C-type lectins. We also show that salivary glycoproteins bind strongly to the surface of transmissible metacyclic trypanosomes. We suggest that although the repertoire of tsetse salivary N-glycans does not change during a trypanosome infection, the interactions with mannosylated glycoproteins may influence parasite transmission into the vertebrate host.

Topics: Animals; Chromatography, Liquid; Concanavalin A; Glycoproteins; Glycoside Hydrolases; Insect Vectors; Lectins, C-Type; Polysaccharides; Saliva; Salivary Glands; Salivary Proteins and Peptides; Tandem Mass Spectrometry; Trypanosoma; Trypanosoma brucei brucei; Trypanosomiasis, African; Tsetse Flies

Concanavalin A (ConA) kills the procyclic (insect) form of Trypanosoma brucei by binding to its major surface glycoprotein, procyclin. We previously isolated a mutant cell line, ConA 1-1, that is less agglutinated and more resistant to ConA killing than are wild-type (WT) cells. Subsequently we found that the ConA resistance phenotype in this mutant is due to the fact that the procyclin either has no N-glycan or has an N-glycan with an altered structure. Here we demonstrate that the alteration in procyclin N-glycosylation correlates with two defects in the N-linked oligosaccharide biosynthetic pathway. First, ConA 1-1 has a defect in activity of polyprenol reductase, an enzyme involved in synthesis of dolichol. Metabolic incorporation of [3H]mevalonate showed that ConA 1-1 synthesizes equal amounts of dolichol and polyprenol, whereas WT cells make predominantly dolichol. Second, we found that ConA 1-1 synthesizes and accumulates an oligosaccharide lipid (OSL) precursor that is smaller in size than that from WT cells. The glycan of OSL in WT cells is apparently Man9GlcNAc2, whereas that from ConA 1-1 is Man7GlcNAc2. The smaller OSL glycan in the ConA 1-1 explains how some procyclin polypeptides bear a Man4GlcNAc2 modified with a terminal N-acetyllactosamine group, which is poorly recognized by ConA.

Topics: Animals; Concanavalin A; Dolichols; Drug Resistance; Glycolipids; Glycosylation; Hemiterpenes; Mutation; Oligosaccharides; Oxidoreductases; Pentanols; Trypanosoma brucei brucei; Trypanosomiasis, African

The type I/type II cytokine balance may influence the development of different subsets of suppressive macrophages, i.e., classically activated macrophages (caMphi, type I) versus alternatively activated macrophages (aaMphi, type II). Recently, we showed that although mice infected with phospholipase C-deficient (PLC-/-) Trypanosoma brucei brucei exhibit a clear shift from type I to the type II cytokine production, wild type (WT)-infected mice remain locked in a type I cytokine response. In the present study, phenotype and accessory cell function of macrophages elicited during WT and PLC-/- T. b. brucei infection were compared. Results indicate that caMphi develop in a type I cytokine environment in the early phase of WT and PLC-/- trypanosome infection, correlating with inhibition of T cell activation triggered by a mitogen, a superantigen, or an antigen. In the late stage of infection, only PLC(-/-)-infected mice resisting the infection develop type II cytokine-associated aaMphi correlating with impaired antigen- but not mitogen- or superantigen-induced T cell activation.

Topics: Animals; Antigen Presentation; Arginase; Ascitic Fluid; Concanavalin A; Enterotoxins; Epitopes, T-Lymphocyte; Female; Interferon-gamma; Interleukins; Lymphocyte Activation; Macrophage Activation; Macrophages, Peritoneal; Mice; Mice, Inbred BALB C; Mitogens; Muramidase; Nitric Oxide; Phenotype; Superantigens; T-Lymphocytes; Trypanosoma brucei brucei; Trypanosomiasis, African; Type C Phospholipases

The relevance of trypanosome-induced immunosuppression in relation to the efficacy of vaccine-induced immunity was studied in mice. Mice were immunised with crude Trichinella spiralis muscle larvae homogenate vaccine and infected with T. spiralis and/or Trypanosoma brucei. Vaccination significantly decreased adult worm burden (p<0. 05) and accelerated worm expulsion in mice infected with T. spiralis only. T. brucei superinfection resulted in monocytosis, suppressed eosinophilia, significant decrease in PCV (p<0.001), higher numbers of adult worms (p<0.001) and failure to expel all adult worms by Day 12 post infection (p.i.). Regardless, they produced anti-Trichinella IgG(1) responses similar to those of the vaccinated non-T. brucei-infected group. T. brucei also suppressed the proliferative responses of spleen cells to stimulation with Con A and T. spiralis antigen, and induced strong production of interferon-gamma (IFN-gamma) in culture supernatants of antigen stimulated spleen and mesenteric lymph node cells. Interleukin-5 (IL-5) production was suppressed by T. brucei in supernatants of Con A- and antigen-stimulated spleen cells. It was concluded that trypanosome infections and the associated immunosuppression are of great practical significance in trypanosome endemic areas, especially with regards to disease control programmes involving vaccine-induced herd immunity.

Topics: Animals; Antibodies, Helminth; Antigens, Helminth; Concanavalin A; Cytokines; Eosinophils; Female; Hematocrit; Immune Tolerance; Lymphocyte Activation; Mice; Models, Immunological; Monocytes; Parasitemia; Protozoan Vaccines; Trichinella; Trypanosoma brucei brucei; Trypanosomiasis, African

The cross talk between the central nervous system (CNS) and the immune system includes among others, the modulation of immune responses by the autonomic nervous system. Here, we investigated the effects of a splenic denervation on cytokine induction in early experimental African trypanosomiasis. Profiles of the cytokine mRNA expression for interleukin (IL)-4, interleukin (IL)-6, interleukin (IL)-10, interleukin (IL)-12, tumour necrosis factor (TNF)-alpha, tumour necrosis factor (TNF)-beta, transforming growth factor (TGF)-beta and interferon (IFN)-gamma were examined at 4 h, 8 h and 12 h postinfection (p.i.), and in noninfected controls. Only IFN-gamma and IL-12 were significantly expressed over noninfected controls. Already at 4 h p.i. both cytokines were expressed and showed more increased levels at 12 h. Sympathetic denervation of the spleen markedly reduced the mRNA expression for both IFN-gamma and IL-12. Con A was used as a positive control and showed an enhanced mRNA expression, which was also suppressed by a splenic denervation. To demonstrate that the mRNA expression had resulted in a cytokine production, we looked for the protein level of IFN-gamma at 4 h p.i. by immunohistochemistry and found increased levels of IFN-gamma, which was also inhibited by the denervation. Sham-operated animals exhibited similar responses as the nondenervated controls. Our data present for the first time very early kinetics for a cytokine gene expression during an experimental African trypanosomiasis. Furthermore, the data suggest a regulatory role for the autonomic nervous system on cytokine responses at both the mRNA and the protein levels.

Topics: Animals; Autonomic Nervous System; Concanavalin A; Cortisone; Cytokines; Denervation; Gene Expression; Interferon-gamma; Interleukin-12; Male; Rats; Rats, Sprague-Dawley; RNA, Messenger; Spleen; Trypanosoma brucei brucei; Trypanosomiasis, African

During murine Trypanosoma brucei infection, macrophages contribute significantly to the inhibition of T cell responses. Although nitric oxide (NO) was shown to play a central role in macrophage-mediated splenic suppression, macrophage-mediated lymph node suppression occurred in an interferon-gamma (IFN-gamma)-dependent manner. In this study, using NO inhibitor NG-monomethyl-L-arginine and anti-IFN-gamma antibodies, the relative contribution of NO and IFN-gamma to the active inhibition of ex vivo concanavalin A-induced T cell proliferation taking place in the spleen and the lymph nodes of T. brucei-infected mice was investigated. NO contributes to the suppressive activity of spleen and lymph node cells only during early-stage infection. The existence of NO-independent suppressive pathway was further evidenced in IFN-gamma(-/-)-infected mice. Spleen cells from such animals do not produce NO but exert significant suppressive activity during the whole course of infection. In contrast in the lymph nodes, no suppressive activity is recorded at any moment of infection. Moreover, addition of exogenous IFN-gamma to cultures containing lymph node cells from IFN-gamma(-/-)-infected mice does not impair proliferation despite NO production in such cultures. Thus during late-stage infection, an IFN-gamma-independent suppressive mechanism is elicited in the spleen, whereas in the lymph nodes, IFN-gamma is required yet not sufficient to inhibit T cell proliferation.

Topics: Animals; Cell Division; Cells, Cultured; Concanavalin A; Female; Indoles; Interferon-gamma; Lymph Nodes; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide; Nitrosamines; Spleen; T-Lymphocytes; Time Factors; Trypanosoma brucei brucei; Trypanosomiasis, African

Infection of mice with African trypanosomes leads to a severe immunosuppression, mediated by suppressor macrophages. Using ex vivo macrophage culture and in vivo cell transfer, it has been shown that nitric oxide (NO) is a potent effector product of these cells and causes both lymphocyte unresponsiveness and dyserythropoiesis. We explored the role of NO in vivo during trypanosome infection using mice with a disrupted interferon-gamma-receptor gene, which were unable to respond with macrophage activation and NO synthesis. These mice were less effective at controlling parasitaemia than the wild types, but showed an improved splenic T-cell responsiveness and reduced anaemia during the early stages of infection. The data indicate that, in the mouse, NO is a significant mediator of immunosuppression only in early infection. Beyond day 10 of infection, NO-independent mechanisms are of primary significance and the control of parasitaemia and T-cell responsiveness are not directly related.

Topics: Anemia; Animals; Cells, Cultured; Concanavalin A; Female; Interferon-gamma; Lymphocyte Activation; Macrophages; Mice; Mice, Knockout; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine; Receptors, Interferon; T-Lymphocytes; Trypanosomiasis, African

The mechanisms regulating resistance or susceptibility to African trypanosomes have been enigmatic. In this study, we assessed the production of several cytokines (IL-4, IFN-gamma, and TNF-alpha) in vivo and in vitro using genetically susceptible (BALB/c) or resistant (C57BL/6) mice infected with cloned Trypanosoma congolense and the role of these cytokines in pathogenesis of this infection. Plasma of infected BALB/c mice contained higher levels of IL-4 and IFN-gamma than the plasma of infected C57BL/6 mice. Conversely, plasma TNF-alpha levels were elevated significantly in the resistant mice relative to the susceptible ones. Splenic IFN-gamma mRNA appeared earlier and were maintained at higher levels in infected BALB/c than in C57BL/6 mice. Both spontaneous and Con A-induced secretions of IL-4 and IFN-gamma by splenocytes from infected BALB/c mice were significantly higher than those from their C57BL/6 counterparts. Con A-induced proliferation of splenocytes from infected BALB/c mice was progressively suppressed. Nitric oxide was not involved in this suppression, but the suppression was positively correlated with IFN-gamma secretion. Addition of neutralizing Abs to IFN-gamma to cultures of Con A-stimulated spleen cells from infected BALB/c mice effectively reversed this suppression. Furthermore, administration of anti-IFN-gamma Abs to BALB/c mice early during infection dramatically shifted the phenotype of these susceptible mice to a more resistant-like phenotype, as expressed by a low and undulating parasitemia and a >300% increase in survival period. These results strongly suggest that the enhanced induction and secretion of IFN-gamma during T. congolense infections contribute to the relative susceptibility of BALB/c mice to the disease.

Topics: Animals; Antibodies, Monoclonal; Concanavalin A; Female; Genetic Predisposition to Disease; Immunity, Innate; Immunosuppressive Agents; Injections, Intraperitoneal; Interferon-gamma; Interleukin-10; Interleukin-4; Liver; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Parasitemia; Phenotype; RNA, Messenger; Spleen; Trypanosoma congolense; Trypanosomiasis, African; Tumor Necrosis Factor-alpha

In this study the involvement of peripheral gamma delta T cells, prepared by flow cytometry, in the immune response of cattle to primary infection with Trypanosoma congolense was assessed. Negligible in vitro proliferative responses were observed in gamma delta T cells isolated from trypanosusceptible Boran (Bos indicus) cattle at all stages examined post-infection when stimulated in vitro with parasite antigens. In contrast, both CD8+ T cells and gamma delta T cells from trypanotolerant N'Dama (Bos taurus) cattle proliferated markedly when stimulated in vitro with a complex of invariant trypanosome antigens with MW between 100,000 and 140,000 (100,000 MW complex). Neither species of cattle exhibited significant T-cell recognition of trypanosome variable surface glycoprotein (VSG). To study further the functional and phenotypic characteristics of the gamma delta T-cell response, four T-cell lines were established from infected N'Dama cattle. These cell lines were comprised of up to 96% gamma delta (WC1+) T cells, the remainder being CD8+ T cells. Two of these gamma delta T-cell lines exhibited 100,000 MW complex antigen specificity which was not major histocompatibility complex (MHC) restricted in one line.

Topics: Animals; Antigens, Protozoan; Cattle; Cell Line; Cells, Cultured; Concanavalin A; Molecular Weight; Receptors, Antigen, T-Cell, gamma-delta; T-Lymphocyte Subsets; T-Lymphocytes; Trypanosoma congolense; Trypanosomiasis, African; Trypanosomiasis, Bovine; Variant Surface Glycoproteins, Trypanosoma; Viral Vaccines

Tsetse-transmitted Trypanosoma congolense infection causes an impairment of in vitro T cell proliferative responses in Boran (Bos indicus) cattle. To assess the importance of this phenomenon as it may relate to the ability of trypanotolerant cattle to control infection with trypanosomes, T cell proliferative responses to mitogenic stimulus with Concanavalin A were measured in N'Dama (Bos taurus) cattle throughout infection. The responses of peripheral blood mononuclear cells from Boran and N'Dama cattle were similar. Depressed proliferative responses were observed with cells of both breeds at 12 days post infection, after which the responses returned to levels similar to those recorded pre-infection. Immunosuppression was also studied in the lymph nodes of a major histocompatibility complex (MHC)-matched pair of N'Dama cattle. Lymph node cells from the infected animal failed to respond to mitogenic stimulus. Co-culture experiments in which the cells from this node were mixed with either lymph node cells or peripheral blood mononuclear cells from the non-infected MHC-compatible animal revealed the presence of suppressor cells, acting in a prostaglandin-independent manner, capable of arresting mitogen-induced T cell proliferation.

Topics: Animals; Cattle; Cells, Cultured; Concanavalin A; Immune Tolerance; Immunosuppression Therapy; Lymph Nodes; Lymphocyte Activation; Major Histocompatibility Complex; T-Lymphocytes; T-Lymphocytes, Regulatory; Trypanosoma congolense; Trypanosomiasis, African; Trypanosomiasis, Bovine

African trypanosomes induce a generalized state of immunosuppression in their mammalian hosts. One characteristic of this is a suppression of lymphocyte responses to mitogen, which is mediated by suppressor macrophages. We investigated the involvement of nitric oxide in this phenomenon. Both peritoneal and splenic cell cultures from infected mice released nitrite and this was inhibitable by NG-monomethyl L-arginine (L-NMMA). The release of nitrite correlated with suppressed splenic T cell proliferative responses to concanavalin A. It was shown that adherent spleen cells from infected mice mediate suppression, which could be abrogated by L-NMMA. These results suggest that in T. brucei infection, the activation of macrophages to produce nitric oxide leads to impaired lymphocyte responses and immunosuppression.

Topics: Animals; Arginine; Concanavalin A; Immune Tolerance; Lymphocyte Activation; Mice; Mice, Inbred C3H; Nitric Oxide; Nitrites; omega-N-Methylarginine; Spleen; T-Lymphocytes; Trypanosoma brucei brucei; Trypanosomiasis, African

A cysteine protease (trypanopain-Tc) with cathepsin-L-like properties has been purified from Trypanosoma congolense. The enzyme has an apparent molecular mass of 31-32 kDa by SDS/PAGE and 66 kDa by gel chromatography. It has a pI 7.4 and a high affinity for concanavalin A. Trypanopain-Tc catalyses the limited proteolysis of a variety of protein substrates such as fibrinogen, serum albumin and trypanosome variant-surface glycoprotein. It has minimal or no activity against casein or elastin. A variety of peptidyl amidomethylcoumarins and peptidyl diazomethanes were used to test the specificity of trypanopain-Tc. The better substrates had Arg or Lys in P1 and hydrophobic amino acids in P2 and P3. The best substrate found for trypanopain-Tc was Z-Phe-Arg-NHMec (Z, benzyloxycarbonyl; NHMec, 7-amido-4-methylcoumarin). The kinetic constants for the hydrolysis of Z-Phe-Arg-NHMec were kcat = 17.4 s-1, Km = 4.4 microM, kcat/Km = 4.0 microM-1.s-1, which are very similar to those of cathepsin L with this substrate. The specific substrates for cathepsin B (Z-Arg-Arg-NHMec) and cathepsin H (Arg-NHMec) were not hydrolysed by trypanopain-Tc under the conditions tested. The pH optimum of trypanopain-Tc against Z-Phe-Arg-NHMec was pH 6.0 but it showed a broad peak of activity extending well into the alkaline region. The enzyme was activated by low-molecular-mass thiol compounds and inhibited by cystatin, L-trans-epoxysuccinyl-4-guanidinobutane (E-64) and a variety of peptidyl diazomethanes. The most effective diazomethane inhibitors (Z-Leu-Leu-Met-CHN2, Z-Leu-Met-CHN2 and Z-Leu-Lys-CHN2, were inhibitory at nanomolar concentrations and were trypanocidal in vitro after 24-48 h incubation in greater than or equal to 20 microM [inhibitor]. However, it is not clear whether the trypanocidal activity of these inhibitors is a consequence of the inhibition of trypanopains or of some other essential proteolytic activities within the parasites.

Topics: Amino Acid Sequence; Animals; Chromatography, Gel; Concanavalin A; Coumarins; Cysteine Endopeptidases; Diazomethane; Electrophoresis, Polyacrylamide Gel; Enzyme Activation; Isoelectric Point; Kinetics; Molecular Sequence Data; Molecular Weight; Peptides; Protease Inhibitors; Rats; Rats, Inbred Strains; Substrate Specificity; Sulfhydryl Compounds; Trypanosoma congolense; Trypanosomiasis, African; Variant Surface Glycoproteins, Trypanosoma

Immunosuppression with respect to those inducible processes which regulate lymphocyte mitogenesis was examined in experimental trypanosomiasis. Splenic leukocytes from Trypanosoma brucei-infected mice showed a decreased proliferative response to the T-cell mitogen concanavalin A. Activated cells secreted normal levels of the endogenous T-cell proliferative signal interleukin-2 (IL-2) and expressed high-affinity IL-2 receptors. However, the ability of activated cells to proliferate in response to exogenous IL-2 was inhibited. These results indicate an impairment of processes which occur after IL-2-receptor binding during lymphocyte mitogenesis. Furthermore, these data indicate that expression of high-affinity IL-2 receptors does not necessarily correlate with an ability to respond to IL-2.

Topics: Animals; Concanavalin A; Immunosuppression Therapy; Interleukin-2; Lymphocyte Activation; Male; Mice; Mice, Inbred C57BL; Receptors, Immunologic; Receptors, Interleukin-2; Trypanosoma brucei brucei; Trypanosomiasis, African

Mitogenic responses of B and T lymphocytes from spleens of rats infected with Trypanosoma brucei rhodesiense were suppressed. Plasma from infected rats suppressed the mitogenic responses of B and T lymphocytes from spleens of normal uninfected rats. Removal of immune complexes from plasma of infected rats significantly reduced the suppressive effect of the plasma on splenic lymphocytes of normal uninfected rats. Normal thymus cells treated with plasma from infected rats and added to cultures of normal spleen lymphocytes inhibited the mitogenic responses of B and T lymphocytes. We suggest that the interaction of immune complexes and Fc or C3b receptors of T lymphocytes resulted in the in vitro induction or activation of T suppressor lymphocytes.

Topics: Animals; Antigen-Antibody Complex; Concanavalin A; In Vitro Techniques; Lipopolysaccharides; Lymphocyte Activation; Male; Rats; Rats, Inbred Strains; Serum Albumin, Bovine; T-Lymphocytes; T-Lymphocytes, Regulatory; Trypanosomiasis, African

In vitro production of interleukin-1 (IL-1) by LPS-stimulated adherent peritoneal exudate and spleen cells and alveolar macrophages, and interleukin-2 (IL-2) by concanavalin A-stimulated splenocytes were measured in resistant (C57BL/6J) and susceptible (A/J) inbred mice during the early stages of subacute infections with the African trypanosome, Trypanosoma congolense. Production of IL-1 was severely depressed in both mouse strains as early as 24 hr after intraperitoneal injection of bloodstream trypanosomes. Similarly, in both mouse strains, an early decline in IL-2 activity was observed, followed by partial recovery then depression to subnormal levels. These changes in measurable IL-1 and IL-2 activity in infected mice concurred with progressive depression in the spleen cell proliferative response to the mitogen concanavalin A.

Topics: Animals; Concanavalin A; Disease Susceptibility; Female; Immune Tolerance; Immunity, Innate; Interleukin-1; Interleukin-2; Lipopolysaccharides; Male; Mice; Mice, Inbred A; Mice, Inbred C3H; Mice, Inbred C57BL; Mitosis; Rats; Spleen; Trypanosoma congolense; Trypanosomiasis, African

Spleen cells from Trypanosoma brucei-infected BALB/c mice were unable to respond to a T-cell mitogen, concanavalin A. Moreover, they were unable to produce detectable amounts of the growth factor required for T cell proliferation, interleukin 2. In addition, supernatants from 24-h in vitro cultures of these cells produced a slight but detectable suppressive activity of the interleukin 2-dependent proliferation of a T-cell line. Infected spleen cells also suppressed the response of T. brucei-immunized spleen cells as well as normal spleen cells to concanavalin A. However, a major difference was shown in the mechanism of the suppression in both systems. Suppression of normal spleen cells required cell-to-cell contact. In contrast, suppression of 30-day T. brucei-immune cells could be mediated by a soluble suppressor factor released by in vitro culture of infected spleen cells. This molecule had an apparent molecular weight of 18,000. Finally, similar suppression could be generated in 30-day T. brucei-immune spleen cells but not in normal cells, with living cells but not with extracts of T. brucei.

Topics: Animals; Concanavalin A; Interleukin-2; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Reference Values; Spleen; T-Lymphocytes; Trypanosoma brucei brucei; Trypanosomiasis, African

Infection of C57BL/10 (B10)3 nu/nu mice with Trypanosoma rhodesiense results in the development of significant T-cell reactivity in spleen and lymph nodes. The proliferative responses to mitogens, such as concanavalin A (Con A) and phytohemagglutinin (PHA), and in mixed-lymphocyte reactions (MLR) to alloantigens are enhanced compared with control uninfected nu/nu mice. These results serve to emphasize the stimulatory nature of trypanosomes on the immune system.

Topics: Animals; Concanavalin A; Female; Interleukin-2; Lymphocyte Activation; Lymphocyte Culture Test, Mixed; Male; Mice; Mice, Inbred C57BL; Mice, Nude; Phytohemagglutinins; T-Lymphocytes; Trypanosomiasis, African

The in vitro proliferative response of peripheral blood lymphocytes from Trypanosoma b. brucei infected goats to mitogens was studied during the course of infection. An inverse correlation was observed between the number of lymphocytes and their capacity to respond to concanavalin A, phytohemagglutinin and pokeweed mitogen. Lymphocyte responsiveness to mitogens was reduced during a period of increased lymphocyte counts. During this period of time only few trypanosomes were detectable in the peripheral blood. Later in the infection, when lymphocytes decreased, mitogen responsiveness and parasitemia increased.

Topics: Animals; Concanavalin A; Goats; Leukocyte Count; Lymphocyte Activation; Lymphocytes; Male; Phytohemagglutinins; Pokeweed Mitogens; Trypanosoma brucei brucei; Trypanosomiasis, African

Glycoproteins of Trypanosoma congolense have been detected on SDS-polyacrylamide gels using the Concanavalin A peroxidase technique. Using [35S]diazoniobenzenesulphonate as a marker for cell surface proteins it was possible to distinguish between internal glycoproteins and the surface coat proteins. On SDS-polyacrylamide gels Con A reacted with the surface coat proteins. Results obtained from Con A-induced agglutination of living trypanosomes indicated that sugars of the surface coat proteins were accessible to Con A. This was reinforced by the cytochemical visualization of Con A binding to the trypanosome surface. The results suggested that the surface coat protein contained alpha-linked D-mannosyl, D-glucosyl, or N-acetyl-D-glucosaminoyl residues, which are exposed exteriorly on the surface coat.

Topics: Animals; Cell Membrane; Concanavalin A; Female; Glycoproteins; Membrane Proteins; Methylmannosides; Mice; Receptors, Concanavalin A; Trypanosoma; Trypanosomiasis, African

Spleen cells from Trypanosoma congolense-infected mice showed a drastic depression in their capacity to respond to B and T lymphocyte mitogens and to allogeneic spleen cells in mixed lymphocyte cultures. Spleen cells from infected mice were also poor stimulators in mixed lymphocyte cultures. The poor responsiveness or stimulation capacity was not due simply to dilution of relevant B or T lymphocytes by the large number of null cells found in the spleens of infected animals. These null cells expressed approximately eight times more H-2 antigen than spleen cells from normal (uninfected) mice and were devoid of Ia antigens.

Topics: Animals; B-Lymphocytes; Concanavalin A; Dose-Response Relationship, Immunologic; Female; Fluorescent Antibody Technique; H-2 Antigens; Immunosuppression Therapy; Lipopolysaccharides; Lymphocyte Culture Test, Mixed; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Inbred CBA; Spleen; T-Lymphocytes; Trypanosomiasis, African