NK1.1+ cells and T-cell activation in euthymic and thymectomized C57BL/6 mice during acute Trypanosoma cruzi infection

Abstract

Cardillo, Fabíola; Mengel Junior, Jose Orivaldo “Documento produzido em parceria ou por autor vinculado à Fiocruz, mas não consta à informação no documento”.Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2017-07-05T14:17:49Z No. of bitstreams: 1 Cardillo F NK1.1+ cells and T-cell....pdf: 194793 bytes, checksum: 33cb19d87590fc6f0383da2c0cc9b020 (MD5)Approved for entry into archive by Ana Maria Fiscina Sampaio ([email protected]) on 2017-07-06T12:30:15Z (GMT) No. of bitstreams: 1 Cardillo F NK1.1+ cells and T-cell....pdf: 194793 bytes, checksum: 33cb19d87590fc6f0383da2c0cc9b020 (MD5)Made available in DSpace on 2017-07-06T12:30:15Z (GMT). No. of bitstreams: 1 Cardillo F NK1.1+ cells and T-cell....pdf: 194793 bytes, checksum: 33cb19d87590fc6f0383da2c0cc9b020 (MD5) Previous issue date: 2002FAPESP, CNPqUniversity of São Paulo. Institute of Biomedical Sciences-IV. Department of Immunology. São Paulo, SP, BrazilUniversity of Sao Paulo. Faculty of Ribeirão Preto. Department of Pharmacology. Ribeirão Preto, SP, BrazilUniversity of Campinas. Institute for Biology. Department of Microbiology and Immunology. Campinas, SP, BrazilUniversity of São Paulo. Institute of Biomedical Sciences-IV. Department of Immunology. São Paulo, SP, BrazilUniversity of São Paulo. Faculty of Medicine of Ribeirão Preto. Department of Morphology. Ribeirão Preto, SP, SP, BrasiUniversity of São Paulo. Institute of Biomedical Sciences-IV. Department of Immunology. São Paulo, SP, BrazilNatural killer (NK) cells may provide the basis for resistance to Trypanosoma cruzi infection, because the depletion of NK1.1 cessla causes high levels of parasitemia in Young C57B1/6 mice infected with T. cruzi. Indeed, NK1.1 cells have been implicated in the early production of large amounts of interferon (IFN)-y, na importante cytokine in host resistance. The NK.1 marker is also expressed on special subpopulations of T cells. Most NK1.1+ T cells are of thymic origin, and their constant generation may be prevented by thymectomy. This procedure, by itself, decreased parasitemia and increased resistance in young mice. However, the depletion of NK1.1+ cells by the chronic administration of a monoclonal antibody (MoAb) (PK-136) did not increase the parasitemia or mortality in thymectomized C57B1/6 mice infected with T. cruzi (Tulahuen strain). To study the cross-talk between NK1.1+ cells and conventional T cells in this model, we examined the expression. of activation/memory markers (CD45RB) on splenic CD4+ and CD8+ T cells from Young euthymic or thymectomized mice with or without depletion of NK1.1+ cells and also in aged mice during acute infection. Resistance to infection correlated with the amount of CD4+ T cells that are already acitivated at the moment of infection, as judged by the number of splenic CD4+ T cells expressing CD45RB-. In addition, the specific antibody response to T cruzi antigens was precocious and na accumulation of immunoglobulin (Ig)M with little isotype switch occurred in euthymic mice depleted of NK1.1+ cells. The data presented here suggest that NK1.1+ cells have importante regulatory functions in euthymic, but not in thymectomized mice infected with T. cruzi. These regulatory functions include a helper activity in the generation of effector or activated/mewmory T cells