Induction of endogenous cytokines in ascites of patients with ovarian cancer by OK-432, a streptococcal preparation.

To clarify the action mechanism of OK-432, OK-432 was intraperitoneally (i.p.) administered to 4 ovarian cancer patients with malignant ascites. In 2 of the 4 patients, 4 types of cytokines (tumor necrosis factor, interleukin 1 beta, interleukin 2, and interferon gamma) were induced in ascites after intraperitoneal injection of OK-432 (i.p. OK-432). In one of these patients, the ascitic supernatant after i.p. OK-432 significantly inhibited colony formation of autologous ascitic tumor cells; the amount of ascites decreased markedly, and the ascitic cytology became negative. In the other 2 patients, only interferon gamma was induced in ascites after i.p. OK-432. In these 2, ascitic supernatant did not inhibit colony formation of autologous ascitic tumor cells. These results indicated that i.p. OK-432 can induce various endogenous cytokines in malignant ascites and that these induced cytokines may contribute to the antitumor effect of i.p. OK-432.