Cell-mediated immune responses to Plasmodium falciparum antigens in adult Gambians.

Peripheral blood mononuclear cells from clinically immune Gambian adults were assayed for in vitro proliferation in response to crude and partially purified Plasmodium falciparum antigens. Lymphoproliferative responses to malaria antigens, lectin mitogens and Candida albicans were compared with those of control donors with no previous exposure to malaria. Cells of malaria-immune individuals were significantly more responsive to conconavalin A, and less responsive to phytohaemagglutinin, than cells from the control donors in both non-immune human serum and autologous serum. Cells from a proportion of immune donors proliferated in response to soluble malaria antigens but a substantial minority did not. Young adults and women were over-represented in the non-responding population. Responses to soluble malaria antigens were depressed in autologous serum compared with normal human serum. Both immune and control cells produced low levels of gamma-IFN when stimulated with crude P. falciparum schizont antigens. Approximately half the immune donors, and none of the controls, produced significant levels of gamma-IFN in response to purified soluble malaria antigen or malaria parasite culture supernatant. There was no direct correlation between lymphoproliferation and gamma-IFN production.