[Specific antibodies to Plasmodium falciparum antigens in immune patients: IV--Cross-sectional analysis of anti-P. falciparum Ab responses in a mesoendemic zone of transmission in Sine-Saloum region].

We report here a comparative study of specific antibody responses to blood stages of P. falciparum in 100 individuals aged from 3 to 76 years, living in the village of Ndiop (an area where parasite transmission is approximately 20 infective bites per year). We have used 2 antigen preparations: crude merozoites and infected erythrocyte ghosts (GRp). High specific antibody responses were found in the villagers' sera, with IgG levels being significantly higher than those directed to the whole P. falciparum schizont Ag preparation; the reverse was found for IgM responses. An imbalanced IgG subclass Ab response was evidenced towards cytophilic IgG1+/gG3+ responses rather than to IgG2+/lgG4+. Mean levels of antibodies increased significantly with age and a strong relationship was evidenced in individual levels of Ab responses towards all the Ag studied. Investigation of the morbidity, recorded as the number of confirmed clinical accesses, underlined a significant inverse relationship only with the levels of IgG to GRp. Taken together, these results proved usefullness of crude P. falciparum Ags for immuno-epidemiological related studies and underlined GRp as a particular target of Ab responses.