Immune response to Plasmodium falciparum antigens in Cameroonian primigravidae: evolution after delivery and during second pregnancy.

Mechanisms responsible for the increase in malaria susceptibility during pregnancy, and in particular during the first pregnancy, have not been elucidated. T and B cell responses to leucoagglutinin, bacille Calmette-Guerin (BCG) and to six Plasmodium falciparum antigens were longitudinally investigated in 33 pregnant women during their first pregnancy, after delivery, and during second pregnancy. Parasitological data obtained from the same women during and after the first pregnancy demonstrated the higher risk of P. falciparum infection during this pregnancy. Plasma levels of antibodies to Pf155/ RESA were lower during pregnancy than after delivery. Conversely, antibodies to P. falciparum asexual blood stages were higher during pregnancy than after delivery, suggesting that during pregnancy the regulation of antibody production may be variously impaired depending upon the antigens. The most striking finding of the present study is the impairment of the IL-2 cellular response during the first pregnancy. Conversely, proliferative responses, as well as IL-4 and interferon-gamma (IFN-gamma) responses, were either unaffected or moderately enhanced. No difference in humoral and cellular responses was observed between first and second pregnancy. The impairment of the IL-2 responses involved the response to malaria peptides and proteins, as well as the response to non-malarial antigens and to the mitogen leucoagglutinin. Thus, the alteration of malaria immunity might rather fall into the general frame of the depression of cellular immunity during pregnancy than involve a specific malaria phenomenon.