Experimental murine Trypanosoma congolense infections. I. Administration of anti-IFN-gamma antibodies alters trypanosome-susceptible mice to a resistant-like phenotype.
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.
Uzonna
J E
JE
Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
Kaushik
R S
RS
Gordon
J R
JR
Tabel
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H
D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D003208:Concanavalin A / Q000494:pharmacology; D005260:Female; D020022:Genetic Predisposition to Disease; D007113:Immunity, Innate; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007274:Injections, Intraperitoneal; D007371:Interferon-gamma / Q000096:biosynthesis / Q000097:blood / Q000276:immunology*; D016753:Interleukin-10 / Q000037:antagonists & inhibitors / Q000097:blood / Q000378:metabolism; D015847:Interleukin-4 / Q000096:biosynthesis / Q000097:blood; D008099:Liver / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018512:Parasitemia / Q000235:genetics / Q000276:immunology / Q000401:mortality; D010641:Phenotype; D012333:RNA, Messenger / Q000096:biosynthesis; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D014348:Trypanosoma congolense / Q000276:immunology*; D014353:Trypanosomiasis, African / Q000235:genetics / Q000276:immunology* / Q000401:mortality; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D000911:Antibodies, Monoclonal; D007166:Immunosuppressive Agents; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D003208:Concanavalin A; D016753:Interleukin-10; D015847:Interleukin-4; D007371:Interferon-gamma