Identification of tumor necrosis factor and lymphotoxin blocking factor(s) in the ascites of patients with advanced and recurrent ovarian cancer.

Ascites obtained from human ovarian cancer patients contains material(s) that inhibit the cytolytic activity of tumor necrosis factor (TNF) and lymphotoxin (LT) in vitro. These inhibitor(s) are found in ascites from ovarian cancer patients and are detected in very low amounts in the ascites from patients with nonmalignant hepatic disease. These ascites TNF/LT blocking factors are heat sensitive and heterogeneous with respect to molecular weight. Kinetic studies indicate these factors inhibited cytolysis at the stage of TNF/LT interaction with membrane receptors on L929 cells. Because TNF and LT are key cytokines in host cell-mediated antitumor mechanisms, factor(s) that inhibit these cytokines could have a profound effect on the tumor host interaction and their presence in the ascitic fluid, should be considered before designing clinical trials that employ intraperitoneal administration of TNF or LT for immunotherapy of ovarian cancer.