Caracterização fenotípica de linfócitos T de memória na infecção por Plasmodium vivax

Abstract

There are indications that immunity induced during primary infection by Plasmodium vivax, a species widely distributed in the world and most prevalent in Brazil, leads to activation of T cells. However, the understanding of the immune mechanisms involved in immunoregulation and immunopathology of vivax still remains incomplete. Memory cells are long lived and recruited during clonal expansion and differentiation of lymphocytes in response to antigenic stimulation. In this study, we evaluate the phenotypic profile of memory T lymphocytes from P. vivax naturally infected patients from Brazilian Amazon. Sixty five patients living in endemic areas with variable number of previous episodes of malaria by P. vivax were assessed. As negative controls, 22 individuals from a non-endemic area were also evaluated.Our results demonstrated that individuals with vivax malaria showed a significant increase of circulating memory CD4+(CD45RO+) lymphocytes. Memory cells from infected patients showed a pattern of central memory, as demonstrated by differential expression of CCR7 and CD62L. Our results showed that infection with P. vivax significantly induces expression of cytokines IFN- and IL-10 by CD4 and increasing concentrations of cellular subpopulations CD4 CD45RA+ and CD4 CD45RO+ and that infection by P. vivax induces proliferation of central memory cells. These results point to the need to generate basic information about the immunological mechanisms in vivax malaria that may inform the dev elopment of future intervention measures.