Rosette formation with mouse erythrocytes. IV. T, B and third population cells in human tonsils.

Mononuclear cells from twenty human tonsils and peripheral blood lymphocytes were examined for T, B and 'third population cells'. Compared with peripheral blood lymphocytes, tonsils were found to have a higher proportion of B lymphocytes with surface IgM, IgD and IgA. Mouse erythrocyte rosette-forming cells were also present in increased proportions. However, 'third population cells' were found in very low proportions. Phagocytic cells as determined by latex ingestion and peroxidase staining were also present in low proportions. The lack of 'third population cells' in human tonsils may establish this organ as one of particular interest in the study of lymphocyte subpopulations because T and B lymphocytes can be purified without contaminating 'third population cells'. The role of the third population of lymphocytes in antibody-dependent cytotoxicity and spontaneous cytotoxicity may be supported by the absence of these functions along with absence of the 'third population' cells from tonsilar lymphoid cells.