Production of IL 2 and IFN-g by T cells from malaria patients in response to Plasmodium falciparum or erythrocyte antigens in vitro

T cells from patients acutely infected with malaria exhibit a disease-related stimulation of DNA synthesis in response to P. falciparum antigen in vitor. This response is weak and short-lived, suggestive of induction of suppressor mechanisms. Exogenous T cell growth factor (IL 2) that was added to antigen-stimulated T cell cultures enhanced proliferation in antigen-responsive cultures, indicating that the lymphocytes expressed IL 2 receptors. There was no obvious correlation between antigen-induced lymphocyte proliferation and the presence of IFN- gamma in the culture supernatants. A high IFN- gamma activity was also seen in antigen-treated cultures from P. falciparum immune donors living in highly endemic malaria areas. In contrast, no IFN- gamma was found in supernatants of antigen-treated T cells from healthy donors or patients with P. vivax malaria. Thus, the IFN- gamma activity of these cultures appears to reflect the presence of antigen-reactive T cells and may be useful as a sensitive indicator of cellular immunity in P. falciparum malaria.