Innunocytological studies on the constituent cells of the secondary nodules in human tonsils.

The rate of presence of surface immunoglobulins (sIg) and incidence of the surface receptors (SRBC-receptor, Fc-receptor and C3 receptor) were examined on the constituent cells of secondary nodules enucleated from human tonsils and foated in suspension. As most of the rosette-forming cells for SRBC-receptor were judged to belong to small round cells, the germinal center was considered to be a "non-T-cell region." The coronal B-lymphocytes and small germinal center cells were fairly matured B-cells because both bore sIg (100%), Fc receptor (25%) and C3 receptor (90-80%), while the former cells were thought to be more matured on the basis of their possession of surface delta-chain. As the large germinal center cells bore sIg (50%) and carried Fc receptor (25%) and C3 receptor (50%), they seemed to be the major immature cells among the cell constituents of the secondary nodules. Moreover, it is presumed that the majority of the large germinal center cells are able to differentiate into coronal B-lymphocytes, probably memory cells, and a minor population of them into cIg-containing cells.