Natural Acquired Immunity to Malaria Antigens among Pregnant Women with Hemoglobin C Trait.

Hemoglobin C is the second most common structural hemoglobinopathy in Africa, and carriers have a reduced risk of severe malaria. However, the effect of HbAC on the antibody response to malaria antigens in pregnancy has not been studied. Here, we measured PfEMP1-specific antibodies in plasma samples from 74 Beninese pregnant women with either HbAA or HbAC. IgG-mediated inhibition of VAR2CSA+ infected erythrocytes adhesion to chondroitin sulfate A (CSA) was also tested. PfEMP1-specific IgG levels to VAR2CSA were significantly lower in HbAC women, suggesting less exposure to VAR2CSA. In contrast, the percentage of VAR2CSA+-infected erythrocytes adhesion to CSA was not different between HbAA and HbAC women. Moreover, IgG levels to PfEMP1 variants associated with severe malaria were not significantly different between groups. The findings indicate similar exposure to Plasmodium falciparum parasites expressing PfEMP1 variants causing severe malaria, and justify more comprehensive studies of hemoglobinopathy-related qualitative and quantitative differences in PfEMP1-specific antibody responses.