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Colony Formation by Subpopulations of Human T Lymphocytes

Twelve human T‐cell lines were derived from cultures stimulated with phytohaemagglutinin (PHA) or with the recall antigen purified protein derivative (PPD), using the one‐step agar colony method, followed by further expansion of individual T‐cell colonies for at least 50 days. As judged by monoclonal antibodies, two of the PHA‐derived T‐cell lines carried the helper–inducer (H–I) phenotype and two the suppressor‐cytotoxic (S–C) phenotype. Four PPD‐derived cell lines displayed the H‐I phenotype, and three of these proliferated specifically when challenged with the recall antigen, whereas the fourth did not. Four PPD‐induced T‐cell lines carried the S‐C phenotype, and only one of these was antigen‐specific. All cell lines with H‐I phenotype displayed helper cell activity as determined by Ig secretion of B lymphocytes stimulated with a T‐cell‐dependent polyclonal B‐cell activator. Cell lines with the S‐C phenotype had no such helper activity and suppressed Ig responses in the presence of freshly isolated T cells. Thus, a good correlation between phenotypic markers and functions was found. T helper cells and T suppressor cells can be differentiated by means of both polyclonal and antigenic stimuli.