Colony formation by subpopulations of human T lymphocytes. II. Characteristics of colony cells and colony suppressor cells.

Phytohaemagglutinin-induced human T-lymphocyte colony formation in semisolid agar culture is the property of erythrocyte rosette-forming cells (E-RFC) negative for the 7S IgG receptor (FcR-). E-RFC positive for the 7S IgG receptor (FcR+), on the other hand, exhibit a limited capacity for colony formation and suppress colonies formed by FcR- E-RFC. T colonies are composed of small lymphocytes and lymphoblasts, the vast majority being negative for the Fc receptor. Most colony cells (86%) carry the Leu 3a antigen, suggesting that they belong to the inducer/helper T-cell subset. FcR+ colony suppressor cells are small, slowly sedimenting cells (sedimentation velocity less than 3.8 mm/h) and are strongly adherent to plastic, and their activity depends on the ability to synthesize DNA.