Partial purification and characterization of a lymphocyte-inhibitory factor(s) in ascitic fluids from ovarian cancer patients

Attempts were undertaken to purify and characterize the lymphocyte-inhibitory activity found in the ascitic effusions from ovarian cancer patients. The active moiety responsible for the inhibition of in vitro lymphocyte function was partially purified from several ascitic fluids by means of concanavalin A-Sepharose 4B (negative) affinity and DE52 ion-exchange chromatography, with final yields of 68 to 74% and 3- to 8-fold increases in specific activity. Analytical polyacrylamide gel electrophoresis showed that the active fraction contained mostly albumins and a-globulins. Further purification by semi-preparative electrophoresis in polyacrylamide gels revealed that the majority of the lymphocyte-inhibitory activity migrated with the albumins, although minor levels of activity were detected in the material which eluted from the a-globulin region. The lymphocyte-inhibitory activity was found to be separable from albumin by means of a rabbit anti-human serum albumin immunoadsorbent column. The active factor which lost activity upon storage at -20° was found to have a molecular size of 40,000 to 80,000 daltons, as estimated by Sephadex G-200 filtration. Attempts to separate an active, small-molecular-size component from fractions containing the inhibitory activity by acid ultrafiltration were largely unsuccessful. Immunodiffusion analysis of the purified fractions following removal of albumin revealed the presence of contaminating amounts of α₁-acid glycoprotein and α₁-antitrypsin. However, levels of these two proteins did not correlate with the presence of lymphocyte-inhibitory activity.