Profiling the PfEMP1-specific IgG response among Ghanaian children with hemoglobin S and C.

Protective immunity to malaria is mainly antibody-mediated and members of the PfEMP1 family are important targets. Abnormal display of PfEMP1 on the infected erythrocytes (IEs) surface and reduced cytoadhesion have been demonstrated in HbAS and HbAC, inherited blood disorders associated with protection against severe P. falciparum malaria. We found that Ghanaian children with HbAS had lower levels of IgG specific for several PfEMP1 variants and that this reactivity increased more slowly with age than in their HbAA counterparts. Moreover, children with HbAS have lower total parasite biomass than those with HbAA at comparable peripheral parasitemias, suggesting impaired cytoadhesion of HbAS IEs in vivo and likely explaining the slower acquisition of PfEMP1-specific IgG in this group. In contrast, the function of acquired antibodies was comparable among Hb groups and appears to be intact and sufficient to control parasitemia via opsonization and phagocytosis of IEs.