Changes in recognition of Plasmodium falciparum antigens by human sera depending on previous malaria exposure.

Naturally acquired immunity against Plasmodium falciparum malaria was analysed by immunoprecipitation and electrophoretic analysis of FUP-1 strain antigens by sera from individuals with different histories of exposure to malaria. Sera from individuals in the process of either acquiring natural resistance (from different age groups in a village of Upper Volta) or losing acquired resistance (adults travelling from hyperendemic areas of Africa to France) were compared. From electrophoretic patterns, it was apparent that two parasite peptides of MW 96 and 100 Kd were preferentially recognized by putatively resistant individuals. Analysis of the reactivity of adult sera from different parts of the world with FUP-1 antigens showed that there were no major geographically restricted antibody specificities. In particular, antibodies reactive with these two peptides were identified in sera of diverse geographic origins. These 96- and 100-Kd peptides of P. falciparum may therefore be antigens related to naturally acquired immune resistance and common to P. falciparum strains of different geographic origin.