Anti-IL-2 treatment impairs the expansion of Treg cell population during acute malaria and enhances the Th1 cell response at the chronic disease

• Grant number: 11/23824-3
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Duration: March 01, 2012 - August 31, 2012
• Field of knowledge: Biological Sciences - Immunology - Cellular Immunology
• Principal Investigator: Maria Regina D'Império Lima
• Grantee: Maria Regina D'Império Lima
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Plasmodium chabaudi infection induces a rapid and intense splenic CD4+ T cell response that contributes to both disease pathogenesis and the control of acute parasitemia. The subsequent development of clinical immunity to disease occurs concomitantly with the persistence of low levels of chronic parasitemia. The suppressive activity of regulatory T (Treg) cells has been implicated in both development of clinical immunity and parasite persistence. To evaluate whether IL-2 is required to induce and to sustain the suppressive activity of Treg cells in malaria, we examined in detail the effects of anti-IL-2 treatment with JES6-1 monoclonal antibody (mAb) on the splenic CD4+ T cell response during acute and chronic P. chabaudi AS infection in C57BL/6 mice. JES6-1 treatment on days 0, 2 and 4 of infection partially inhibits the expansion of the CD4+CD25+Foxp3+ cell population during acute malaria. Despite the concomitant secretion of IL-2 and expression of high affinity IL-2 receptor by large CD4+ T cells, JES6-1 treatment does not impair effector CD4+ T cell activation and IFN-gamma production. However, at the chronic phase of the disease, an enhancement of cellular and humoral responses occurs in JES6-1-treated mice, with increased production of TNF-alpha and parasite-specific IgG2a antibodies. Furthermore, JES6-1 mAb completely blocked the in vitro proliferation of CD4+ T cells from non-treated chronic mice, while it further increased the response of CD4+ T cells from JES6-1-treated chronic mice. We conclude that JES6-1 treatment impairs the expansion of Treg cell population during early P. chabaudi malaria and enhances the Th1 cell response in the late phase of the disease. (AU)