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  • Title: CTLA-4 regulates the murine immune response to Trypanosoma cruzi infection.
    Author: Graefe SE, Jacobs T, Wächter U, Bröker BM, Fleischer B.
    Journal: Parasite Immunol; 2004 Jan; 26(1):19-28. PubMed ID: 15198642.
    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.
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