Natural killer-like cytotoxicity of human T-cell clones against various target cells.

MLC-T cells from two different donors were cultured after limiting dilution (0.3 cells/well) in medium containing T-cell growth factor. Clones showing lytic activity against K-562 in a preliminary screening were expanded and tested against various NK-sensitive target-cell lines (Chang, T-24, Daudi, and Molt-4) and phytohaemagglutinin blasts derived from the stimulator cells. Ten growing clones maintained their activity against K-562 and were able to lyse the other cell lines. A significant heterogeneity was nevertheless noticed in the lytic efficiency of the different clones against the various target cells. Taken together, our data indicate that single clones are able to lyse different NK-sensitive targets.