Essential Role of γδT Cells In Naturally Acquired Immunity to Falciparum Malaria

Abstract 4877

It is important to understand the mechanisms of naturally acquired immunity to malaria for the development of effective malaria vaccines. We have demonstrated that γδT cells expanded in the peripheral blood of the falciparum malaria patients in Thailand but did not expand in patients living in malaria endemic areas of Laos. However, the percentage of Vγ9^-T cells, a γδT cell subset, increased in the Laos patients. The levels of naturally acquired antibodies to crude P. falciparum (Pf) antigens also increased with an age dependent manner in individuals living in endemic areas of Laos. In this study, we further investigated the role of Vγ9^-T cells in naturally acquired immunity to the falciparum malaria. The peripheral blood lymphocytes (PBLs) and plasma obtained from hospitalized uncomplicated falciparum malaria patients (UMPs) and severe falciparum malaria patients (SMPs) in Thailand and from non-hospitalized UMPs living in endemic areas of Laos were analyzed. The plasma levels of IL-10, which is anti-inflammatory cytokine and associated with antibody production from B cells, were elevated in both hospitalized and non-hospitalized falciparum malaria patients. There was a correlation between the levels of IL-10 and the percentage of Vγ9^-T cells in γδT cells. IL-10 and Pf specific antibodies were detected only in culture supernatant of PBLs from non-hospitalized UMPs in the presence of IL-2 for 2 wks. These results indicate that Vγ9^-T cells may contribute to acquiring natural immunity to malaria.