Effects of intraperitoneal administration of OK-432 for patients with advanced cancer.

The effects of intraperitoneal administration of OK-432 on tumor cells in ascites, in relation to the infiltration of effector cells and on the immune responses of the host, particularly, with regard to immune suppressive mechanisms, were investigated in 25 patients with cancerous ascites. The effects of OK-432 depended on frequency of the repeated and continuous administrations through a tube placed in the peritoneum during laparotomy. Infiltrations of neutrophils and lymphocytes were observed in the ascites within a short period after the administration and monocyte infiltration followed. Disappearance of tumor cells correlated well with the infiltration of these cells. No marked changes in the proliferative responses of peripheral blood lymphocytes were noted and decreases in serum inhibitory factor levels in sera were observed in patients given larger doses of OK-432. A marked reduction in Concanavalin-A-induced suppressor cell activities was observed after OK-432 administration. OK-432 administration probably leads to a disappearance of tumor cells by enhancing peritoneal effector cell activities and by inhibiting the induction of suppressor cell activities, in a dose dependent manner.