Characterization of glycoconjugates released in vitro by human ovarian carcinoma cells isolated from effusions

Ovarian carcinoma cell clusters were isolated from patient effusions. The glycoconjugates released to culture medium in vitro were characterized by electrophoretic, immunoassay and gel filtration procedures. Metabolically radiolabelled glycoconjugates were heterodisperse with respect to molecular weight and this heterodispersity was independent of incubation time in vitro. This heterodispersity was also characteristic of mixed Mullerian tumor cells of endometrial origin whereas mesothelial cells released a discrete glycoconjugate of MW 65-70 kDa. Multiple Coomassie blue-stained polypeptides were released by the carcinoma cells. These polypeptides were not adsorbed serum components as assessed by immunodiffusion analyses. Periodic acid-Schiff-reactive macromolecules appeared only at the top of electrophoresis gels. The high molecular weight glycoconjugates synthesized by ovarian carcinoma cells precipitated with an effusion globulin fraction at low ionic strength, but the low molecular weight components (40-70 kDa) were soluble. Immunoprecipitation with anti-Ig failed to precipitate carcinoma glycoconjugates. Antisera raised against the released carcinoma macromolecules precipitated carcinoma glycoconjugates and normal ovarian polypeptides. Antisera raised against normal ovarian macromolecules precipitated ovarian polypeptides but reacted only slightly with carcinoma glycoconjugates. Immunodiffusion analyses showed the presence of alpha 1-acid glycoprotein and carcinoembryonic antigen (CEA)-like components in the carcinoma glycoconjugates. The presence of CEA-like glycoconjugates was confirmed by immunoprecipitation. The antigens and antisera for different histologic types of ovarian carcinoma were cross-reactive. The presence of beta 2-microglobulin suggested that some of the glycoconjugates were shed from the cell surface.