INHIBITION OF PLASMODIUM-FALCIPARUM IN-VITRO BY HUMAN GAMMA-DELTA T-CELLS

As assessed by flow cytometry, human gamma delta T cells were shown he re to inhibit replication of blood-stage Plasmodium falciparum in vitr o in a dose-dependent fashion; no other leukocyte population tested wa s suppressive. Replication of intraerythrocytic stages of the parasite (rings, trophozoites, and schizonts) was not affected by coculture wi th gamma delta T cells nor were erythrocytes damaged by this coculture , indicating that the targets recognized by gamma delta T cells are ex tracellular merozoites in transit to new host erythrocytes. Moreover, parasite inhibition requires contact between gamma delta T cells and m erozoites. These findings suggest that gamma delta T cells may exert a protective effect in immunity to malaria.