Lysis of autologous tumor cells by high‐density lymphocytes is potentiated by the streptococcal preparation OK432 (picibanil)

In experiments performed with tumor cells isolated from surgical specimens and lymphocytes collected at the time of surgery, tumor cells are often lysed by blood lymphocytes. Some of the effectors are present in the high‐density T‐cell subset. This population has little or no anti‐K562 activity. For the auto‐tumor lysis of T‐cells with high density, CD8‐positive cells are mainly responsible. OK432 pretreatment of the effectors potentiates the existing lytic function or induces it in cases in which the cells have no such function. In general, the potentiating effect reflects inherent patterns of cytotoxicity. In contrast to the lysis of autologous tumor cells, cells with low but not high density were induced to lyse K562.