IgGl and IgG2 antibody responses toPlasmodium falciparumexoantigens correlate inversely and positively, respectively, to the number of malaria attacks

In Manarintsoa, near Antananarivo, Madagascar, two groups of patients were defined in terms of malaria clinical immune status: Group MA+ consisted of 36 patients who suffered from between one to four malaria attacks (MA) during the 20-week study, and Group MA- who comprised of 48 persons who did not have any malaria attacks during this time. In group MA+, IgM and IgG antibody levels to Plasmodium falciparum exoantigens (E-Ag) were inversely related to the number of malaria attacks. The level of IgM antibodies were significantly higher in group MA+. In contrast, IgG, IgG1, IgG2, IgG3 and IgG4 antibodies to E-Ag were significantly higher in group MA-. The level of IgG1 antibodies was inversely correlated, and IgG2 antibodies were positively correlated to the number of malaria attacks.