Augmentation of autologous tumor killing activity of tumor-associated large granular lymphocytes by the streptococcal preparation OK432.

In vitro overnight exposure to the streptococcal preparation OK432 of blood and tumor-associated lymphocytes enhanced their lytic activity against autologous, freshly isolated tumor cells from malignant pleural effusions of cancer patients. This enhancement was mediated through factors that were distinct from interferon (IFN) and interleukin 2 (IL 2). Treatment with IFN-alpha, -beta, or -gamma, or IL 2 failed to augment autologous tumor killing (ATK) activity, although the treatment enhanced natural killer (NK) activity. Intrapleural (i.pl.) injection of OK432 induced or enhanced ATK and NK activities of effusion large granular lymphocytes (LGL) in patients who showed a reduction or disappearance of effusion tumor cells. No such increase in ATK and NK activities was seen with effusion LGL of patients who had no clinical benefit from i.pl. OK432 therapy. Blood ATK and NK activities were not consistently modified by the therapy. These results indicate that i.pl. administration of OK432 induces an augmentation of ATK activity of effusion LGL, which may be involved in the elimination of effusion tumor cells. The data also suggest that the host immune defense against tumor may be better represented by tumor-associated lymphocytes than by blood lymphocytes, and that it is important to examine the effect of biological response modifiers on ATK activity of tumor-associated effector cells.