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  • Title: Increased susceptibility of Fas ligand-deficient gld mice to Trypanosoma cruzi infection due to a Th2-biased host immune response.
    Author: Lopes MF, Nunes MP, Henriques-Pons A, Giese N, Morse HC, Davidson WF, Araújo-Jorge TC, DosReis GA.
    Journal: Eur J Immunol; 1999 Jan; 29(1):81-9. PubMed ID: 9933089.
    Abstract:
    Infection of BALB/c mice with Trypanosoma cruzi resulted in up-regulated expression of Fas and Fas ligand (FasL) mRNA by splenic CD4+ T cells, activation-induced CD4+ T cell death (AICD), and in Fas: FasL-mediated cytotoxicity. When CD4+ T cells from infected mice were co-cultured with T. cruzi-infected macrophages, onset of AICD exacerbated parasite replication. CD4+ T cells from T. cruzi-infected FasL-deficient BALB gld/gld mice had no detectable AICD in vitro and their activation with anti-TCR did not exacerbate T. cruzi replication in macrophages. However, infection of BALB gld/gld mice with T. cruzi resulted in higher and more prolonged parasitemia, compared to wild-type mice. Secretion of Th2 cytokines IL-10 and IL-4 by CD4+ T cells from infected gld mice was markedly increased, compared to controls. In addition, in vivo injection of anti-IL-4 mAb, but not of an isotype control mAb, reduced parasitemia in both gld and wild-type mice. These results indicate that, besides controlling CD4+ T cell AICD and parasite replication in vitro, an intact Fas: FasL pathway also controls the host cytokine response to T. cruzi infection in vivo, being required to prevent an exacerbated Th2-type immune response to the parasite.
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