Human antibody responses to Pfs 230, a sexual stage-specific surface antigen of Plasmodium falciparum: non-responsiveness is a stable phenotype but does not appear to be genetically regulated.

The 230 kD gamete surface protein of the malaria parasite Plasmodium falciparum (Pfs 230) is a target of transmission blocking antibodies. Anti-Pfs 230 antibodies are induced following natural infection with malaria but are not found in all P. falciparum-exposed individuals. In this study we have shown that approximately 40% of malaria-exposed Gambians do not make antibodies to the native Pfs 230 molecule. This phenotype is remarkably stable over time and does not appear to be related to age, malaria exposure or major histocompatibility complex genotype. Comparison of antibody responses in twins indicates that the anti-Pfs 230 response is not strictly genetically controlled, but a high degree of concordance within both dizygous and monozygous twin pairs suggests that factors associated with exposure to malaria in childhood may be important in determining the subsequent immune response.