Familial correlation of immunoglobulin G subclass responses to Plasmodium falciparum antigens in Burkina Faso.

Host genes are thought to determine the immune response to malaria infection and the outcome. Cytophilic antibodies have been associated with protection, whereas noncytophilic antibodies against the same epitopes may block the protective activity of the protective ones. To assess the contribution of genetic factors to immunoglobulin G (IgG) subclass responses against conserved epitopes and Plasmodium falciparum blood-stage extracts, we analyzed the isotypic distribution of the IgG responses in 366 individuals living in two differently exposed areas in Burkina Faso. We used one-way analysis of variance and pairwise estimators to calculate sib-sib and parent-offspring correlation coefficients, respectively. Familial patterns of inheritance of IgG subclass responses to defined antigens and P. falciparum extracts appear to be similar in the two areas. We observed a sibling correlation for the IgG, IgG1, IgG2, IgG3, and IgG4 responses directed against ring-infected-erythrocyte surface antigen, merozoite surface protein 1 (MSP-1), MSP-2, and P. falciparum extract. Moreover, a parent-offspring correlation was found for several IgG subclass responses, including the IgG, IgG1, IgG2, IgG3, and IgG4 responses directed against conserved MSP-2 epitopes. Our results indicated that the IgG subclass responses against P. falciparum blood-stage antigens are partly influenced by host genetic factors. The localization and identification of these genes may have implications for immunoepidemiology and vaccine development.