Phenotype and function of B cells in children infected with P. falciparum malaria

In parallel, we (Dr. Eunice Nduati, Agnes Gwela, Britta Urban) determine the phenotype and function of B cells in response to infected red blood cells using an in vitro activation assay and flow cytometry in healthy children and adults and in children with acute malaria and after convalescence. The aim of this study is to elucidate the defect that underlies the short-lived nature of antibody responses to many parasite antigens in children living in endemic areas. We have shown that memory B cells to the parasite can be detected in children for at least four months after an acute malaria episode indicating that memory B cells are generated and maintained. Therefore, acute infection may interfere either with the generation or maintenance of long-lived plasma cells and antibody levels in plasma are dependent on the differentiation of memory B cells to short-lived plasma cells at the time of acute infection (PhD thesis, Eunice Nduati). Interestingly, memory B cells differentiated readily in response to parasite and differentiation resulted in a high proportion of plasma cells secreting IgM similar to TLR9-dependent activation of memory B cells by CpG. We are now investigating the role of IgM memory B cells in immunity to malaria. Finally, we observed that BAFF, an essential cytokine for differentiation and survival of B cells, is elevated in plasma of children with acute malaria but expression of their cognate receptors is reduced on B cells (PhD thesis, Eunice Nduati).