Surface Markers on Human B and T Lymphocytes

The distribution of surface immunoglobulin and receptors for Fc, C3, and sheep erythrocytes (SRBC) on resting and blast‐transformed peripheral lymphocytes was investigated. The following conclusions were reached. [1] SRBC receptors were retained on all blast‐transformed T lymphocytes. No such receptors were found on normal or neuraminidase‐treated B lymphocytes. [2] Receptors for Fc and C3 were found to be expressed on the same resting lymphocytes, which formed a subpopulation that did not entirely overlap with surface immunoglobulin‐positive B cells. Owing to this and the fact that Fc/C3 receptors were lacking on almost all B blast cells, as well as for other reasons elaborated in the text, it is argued that caution must be taken when these receptors are used as B‐cell markers. [3] A comparison among C3 indicator cells prepared with human or mouse complement showed that these detected the same lymphocyte subpopulatiom [4] B blast cells, induced by 72‐hr pokeweed mitogen cultures, were found to carry detectable amounts of surface immunoglobulin. [5] Phagocytic leukocytes were found to be conveniently detected by scoring the number of cells with internal C3 indicator cells after osmotic lysis of externally bound indicator cells.