TUMOR-NECROSIS-FACTOR AND INTERLEUKIN-6 PRODUCTION INDUCED BY COMPONENTS ASSOCIATED WITH MEROZOITE PROTEINS OF PLASMODIUM-FALCIPARUM

P. falciparum merozoite antigens, merozoite surface protein-1 (MSP-1) and rhoptry associated protein-1 (RAP-1), were shown to be liberated i nto the supernatant of in vitro parasite cultures and to be included i n the endotoxin-like exoantigen complex, previously designated Ag7. Ma terial affinity purified from culture supernatants, using immobilized monoclonal antibodies specific for RAP-1 or MSP-1, stimulated normal h uman mononuclear cells to produce TNF and IL-6 in vitro. However, stim ulation of TNF was absent, and that of IL-6 was reduced, when the anti gens were purified from detergent extracts of infected erythrocytes. T hese results indicate that the RAP-1 and MSP-1 proteins themselves do not stimulate the production of TNF. Instead, other components associa ting with these exoantigens may be responsible for the TNF production. Mouse antisera blocking TNF production stimulated by P. yoelii exoant igens also blocked TNF production stimulated by material affinity puri fied from P. falciparum culture supernatants using RAP-1 specific mono clonal antibody, indicating the conserved structure of the TNF inducin g component.