Allocytotoxic T cell clones: both Leu 2+3- and Leu 2-3+ T cells recognize class I histocompatibility antigens.

T cell clones were selected which were cytotoxic for human class I major histocompatibility target antigens. Specificity was based on target cell panel studies and inhibition by monoclonal antibodies to class I determinants. Eight clones were Leu 2+3-. The cytotoxicity of these clones was inhibited by antibody to the Leu 2 antigen. Two clones expressed the Leu 2-3+ phenotype and were not inhibited by anti-Leu 2a or anti-Leu 3a antibodies. These studies indicate that class I-specific cytotoxic T cells are distributed in both T cell subsets, though predominantly in the Leu 2+3- group. In addition, these studies suggest that the Leu 3 molecule may not function in identical fashion in Leu 3+ cytotoxic T cells, which recognize class I target antigens, as in those which recognize class II targets.