Plasma immunoglobulin concentrations in a West African (Gambian) community and in a group of healthy British adults.

Plasma concentrations of IgG, IgA, IgM and IgD of 1123 members of a native West African (Gambian) community and of ninety-one British adults were measured using a single radial diffusion technique. The African plasmas showed changes of immunoglobulin concentration with age which were characteristic for each class. Gambian children attained adult levels of IgG by about the 5th year of age. Mean IgG concentration in Gambian adults was approximately twice that of the British adults. IgA was not detected in Gambian children in the first few days of life. British and Gambian adults showed a similar broad range of IgA concentrations, and in Gambians the range broadened progressively with increasing age. IgM was detected in all Gambian sera, including that from the youngest children. Values rose rapidly during the first 3 months of life. In Gambian adults a broad range of values was found, with higher values becoming more frequent in the elderly. IgM levels in some Gambian sera were conspicuously increased compared with the British sera, but the anticipated increase of 19S proteins in the ultra-centrifuge was not found. High IgM levels were not associated with evidence of infection with , nor were the findings typical of Walden-ström's macroglobulinaemia. IgD was not detected in Gambian children less than 2 months of age, but a broad range of values was found in childhood and adolescence. In adults higher levels occurred less frequently and the distribution of levels was similar to that of the British population. The significance of these findings is discussed.