Análise dos parâmetros parasitológicos e hematológicos e das subpopulações de células Th1, Th2, Th17, Treg e T citotóxica em pacientes com malária vivax

Abstract

Malaria is a parasitic disease of major global importance and is responsible for leading causes of morbidity and mortality in tropical and subtropical areas of the world. Despite efforts to control the infection in different endemic areas, malaria continues to expand, and the traditional transmission control measures are ineffective. The immune response in malaria is complex, and the mechanisms of activation and regulation of T lymphocytes and their cytokines are still poorly understood. The objective of this study was to evaluate the correlation of parasitemia with the number of platelets and leukocytes, and identify and quantify specific subpopulations of Th1, Th2, Th17 and Treg cells in infection by P. vivax. Evaluating the parasitemia and the number of platelets was verified that there is a negative correlation (p<0,0005) between these parameters and that, dependent of the number of parasites, vivax malaria patients showed higher degree of thrombocytopenia (p<0,0001). Evaluating the number of parasites and total leukocytes was observed no correlation between these parameters in patients with vivax malaria. Moreover, it was also not detected change in the number of total leukocytes when compared to healthy controls. Subsequently, was performed by flow cytometry, identification and quantification of T cell subsets: Th1 (CD3+CD4+IFN-γ+), Th2 (CD3+CD4+IL4+), Th17 (CD3+CD4+IL-17+), Treg (CD4+CD25+CD127-) and cytotoxic (CD3+CD8+) in patients with vivax malaria and healthy controls after lymphocyte culture previously isolated from peripheral blood, to verify the change in the number of these subpopulations lymphocytes by infection with P. vivax. The percentage of IL-10 was also evaluated on Treg cells (CD4+CD25+CD127+IL-10). Individuals infected with P. vivax showed increased percentage of Th1 and cytotoxic T cells. The percentage of Th2, Th17 and Treg cells did not differ between groups. However, the percentage of Treg cells that produce IL-10 cytokine was increased in patients with vivax malaria compared to healthy controls. Finally, the evaluation of the number of CD4+ T and CD8+ T cells indicated that there were no differences between the proportion of these lymphocytes in healthy controls or during the infectious process induced by P. vivax. In conclusion, vivax malaria patients show an increase in the number of cytotoxic T cell, Th1 and Treg cells (CD4+CD25+CD127-) producers of interleukin-10, indicating that infection with P. vivax activate specific cells which can participate in the immunoregulation against this parasite.