Inhibition of in Vitro Lymphocyte Function by Cystic and Ascitic Fluids from Ovarian Cancer Patients

Ascitic and cystic effusions from patients with benign and malignant ovarian neoplasms were tested for the presence of immunosuppressive activity as measured by the inhibition of in vitro lymphocyte function. A substantial percentage of ascites fluids (12 of 26) and a few (2 of 11) cystic effusions from primary ovarian tumors were found to contain a factor(s) which was capable of inhibiting the blastogenic response of normal lymphocytes. The presence of lymphocyte-inhibitory activity was not limited to fluids derived from malignant neoplastic processes but was also found in effusions associated with benign ovarian disorders. Inhibition of the lymphocyte response by active ascites fluids inversely correlated with the cell and serum concentrations used in the assay system. Absorption of the active moiety from the inhibitory ascites fluids by normal lymphocytes was found to be time and temperature dependent and did not appear to be readily reversible. The factors) responsible for the inhibition of lymphocyte function was non-dialyzable, was noncytotoxic, and had an apparent molecular size between 50,000 and 100,000 as estimated by Diaflo ultrafiltration. The inhibitory activity was found to be moderately sensitive to extreme acid and alkaline conditions and was stable to a 56°, 30-min heat treatment. Preliminary results revealed that the ascites fluids containing lymphocyte-inhibi-tory activity inhibited the proliferation of both T-and B-lympho-blastoid cell lines as measured by [³H]thymidine incorporation. However, no effect was observed on the proliferation of epithelioma and oligodendroglioma cell lines.