Surface markers of cloned human T cells with various cytolytic activities.

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Abstract
Human T cells stimulated in secondary allogeneic mixed lymphocyte culture (MLC) were cloned under limiting conditions in microculture systems using T cell growth factor and irradiated allogeneic cells. Clones with lytic activity against phytohemagglutinin-induced blast cells bearing the stimulating alloantigen(s) (cytotoxic T lymphocyte [CTL] activity), L1210 mouse lymphoma cells coated with rabbit antibody (antibody-dependent cell-mediated cytotoxicity [ADCC]) or K562 human [erythroleukemia] target cells were selected, expanded and then analyzed for different surface markers, including rosette formation with sheep erythrocytes (E rosettes), receptors for the Fc portion of IgG or IgM (Fc.gamma.R and Fc.mu.R), and a group of antigens recognized by monoclonal antibodies including Ia, 4F2, OKT8 and OKT4. All the cytotoxic cells were E rosette+, Ia+, and 4F2+. Expression of Fc.gamma.R was restricted to the clones active in ADCC. CTL clones were either OKT8+ and OKT8-. Three of the OKT8- CTL clones were OKT4+. Some cytolytic clones devoid of specific CTL activity were OKT8+. The claim that human CTL are OKT8+, OKT4 and Ia- is apparently not supported by the analysis of their phenotype at the clonal level.