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London School of Hygiene & Tropical Medicine Malaria Centre

Malaria research in immunology and vaccination

Dynamics of the breadth and magnitude of circulating memory B cell responses to Plasmodium falciparum in an area of low malaria transmission.

LSHTM investigators:
Sarah Nogaro, Eleanor Riley, Julius Hafalla, David Conway & Kevin Tetteh.
External collaborators:
Michael Walther & Brigitte Walther (Medical Research Council, The Gambia); Edmond Remarque (Biomedical Primate Research Centre, The Netherlands).
Funding body:
Medical Research Council, UK.

Immunity against symptoms of malaria requires repeated exposure, suggesting either that the parasite is poorly immunogenic or that the development of effective immune responses to malaria may be impaired.

To begin to test these two hypotheses, we carried out two age-stratified cross-sectional surveys of anti-malarial humoral immune responses in a Gambian village where P. falciparum malaria transmission is low and sporadic. Circulating antibodies and memory B cells (MBC) to four malarial antigens were measured using ELISA and cultured B cell ELISpot. The proportion of individuals with malaria-specific MBC and antibodies, and the average number of antigens recognised by each individual, increased with age but the magnitude of these responses did not. Malaria-specific antibody levels did not correlate with either the prevalence or median number of MBC, indicating that these two assays are measuring different aspects of the humoral immune response.  Among those with immunological evidence of malaria exposure (defined as a positive response to at least one malarial antigen either by ELISA or ELISPOT), the median number of malaria-specific MBC was similar to median numbers of diphtheria-specific MBC, suggesting that the circulating memory cell pool for malaria antigens is of similar size to that for other antigens.