title: CTLA-4 regulates the murine immune response to Trypanosoma cruzi infection.
abstract: Infection with Trypanosoma cruzi causes a profound suppression of T cell responsiveness to polyclonal or antigenic stimuli. In this study, we quantified expression of the negative T cell regulatory molecule CTLA-4 in T. cruzi infected mice and analysed its influence on the immune suppression. Levels of splenic CTLA-4 expression were highest around day 10 after infection, reaching 5% in resistant B6D2F1 mice, but exceeding 10% of CD4(+) T cells in C57BL/6 mice that were susceptible to mortal disease. The proliferative response of explanted splenocytes to CD3-mediated stimulation was strongly suppressed in both the susceptible and the resistant strains. Blockade of CTLA-4 in vitro with a monoclonal antibody affected neither proliferative response nor cytokine production (IFN-gamma, IL-4 and IL-2) by splenic T cells from infected C57BL/6 mice. Treatment of mice with anti-CTLA-4 antibody on the day of infection decreased IFN-gamma production and reduced mortality by about 50%. We conclude that high CTLA-4 expression is a hallmark of severe disease in murine T. cruzi infection, and that CTLA-4 has a regulative influence at the early stages during priming of the immune reaction to the parasite, augmenting a strong Th1-biased response.
authors.affiliation: Bernhard-Nocht-Institute, Department of Immunology, Hamburg, Germany. seb@bni-hamburg.de
authors.forename: S E B
authors.initials: SE
authors.lastname: Graefe
authors.forename: T
authors.initials: T
authors.lastname: Jacobs
authors.forename: U
authors.initials: U
authors.lastname: Wächter
authors.forename: B M
authors.initials: BM
authors.lastname: Bröker
authors.forename: B
authors.initials: B
authors.lastname: Fleischer
mesh_terms: D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000096:biosynthesis* / Q000276:immunology*; D015704:CD4 Antigens / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D016827:CD8 Antigens / Q000032:analysis; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D060908:CTLA-4 Antigen; D014355:Chagas Disease / Q000276:immunology* / Q000469:parasitology; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D007371:Interferon-gamma / Q000032:analysis / Q000096:biosynthesis; D007376:Interleukin-2 / Q000032:analysis / Q000096:biosynthesis; D015847:Interleukin-4 / Q000032:analysis / Q000096:biosynthesis; D016131:Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013154:Spleen / Q000166:cytology / Q000276:immunology; D014349:Trypanosoma cruzi / Q000276:immunology* / Q000472:pathogenicity
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D015704:CD4 Antigens; D016827:CD8 Antigens; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D007376:Interleukin-2; D015847:Interleukin-4; D007371:Interferon-gamma