| Abstract: | A series of 4 cell surface marker systems have been developed and applied to human thymus, tonsil and purified blood lymphocyte populations. Double fluorochrome and mixed fluorochrome-rosette tests were used to determine cellular specificity and interrelationship of cells bearing the different markers and the results confirmed by a variety of cell separation procedures. Anti-brain antisera were, after appropriate absorption, T cell-specific and identified the same population as that forming rosettes with sheep erythrocytes. This T cell population was quite distinct from those cells, presumably B lymphcytes, with cell surface immunoglobulin readily demonstrable by fluorescence. A small proportion of “lymphoid” cells (“null” cells) lacked all three markers. Heat-aggregated human IgG (AggHIgG) was also used as a presumptive B cell marker and the results indicate that although most B lymphocytes do bind AggHIgG, presumably via an Fc receptor, a small proportion of thymocytes and presumptive T cells in tonsils also appear to possess a similar receptor. Almost all of these cells in tonsil were in fact lymphoblasts, thus raising the possibility that an Fc receptor is exposed or expressed on T lymphocytes when these cells are activated. |
