[Percent distribution of B-Lymphocytes in human tonsils at various ages].

B-Lymphocytes of the classes G, M and A were determined by use of heavy-chain-specific fluorescent antisera from 67 children between 2 and 14 years of age and from 15 adults up to 60 years of age. Tonsils from which viable cell suspensions were investigated for B-Cells were classified histologically, according to their degree of lymphatic hyperplasia and inflammation. With increasing age, a statiscally significant decrease in percent G- and M-cells was observed while A-cells remained unchanged. With increasing severity and extent of inflammation and lymphatic hyperplasia, there occured a mild increase in percent M-cells. G-cells did not exhibit major changes under such conditions. It is suggested, that the tonsil may represent an early and fast reaching immunocompetent organ primarily determined for the production of large molecular IgM and IgA of less specificity.