OK-432 and IL-2-augmental cytotoxicity of human natural killer cells and cytotoxic T lymphocytes at the clonal level

The biological response modifiers OK-432 and interleukin-2 (IL-2) were found to enhance the lytic capacity of cloned CD3- natural killer (NK) cells and CD3+ T cells. With respect to NK cells, only those clones with a high proliferative capacity and cultured without phytohaemagglutinin (PHA) responded with enhanced lytic capacity to OK-432. OK-432, but not IL-2, was found to augment the antibody-dependent cellular cytotoxicity of cloned NK cells. With T-cell clones, OK-432 augmented the cellular cytotoxicity of CD3+8+ but not that of CD3+4+ cytotoxic T lymphocytes, while IL-2 augmented the cytotoxicity of both types of clone. Taken together, these results indicate that OK-432-augmented lytic capacity is not restricted to NK cells and its pathway of action may be independent of IL-2.