Identification of a meiotically expressed carbohydrate antigen in ovarian carcinoma: II. Association with proteins in tumors and peritoneal fluid.

A monoclonal antibody developed against a meiotically expressed porcine oocyte carbohydrate antigen has been shown to recognize an antigen in ovarian surface epithelial cells (OSE) of numerous mammalian species, including the non-human primate and the human (1). Although most of the ovarian surface epithelial cells are lost during aging in the human, a few cells may remain in ovarian crypts. Because the majority of ovarian carcinomas are thought to be derived from the OSE cells in aging women the PS1 antibody has been used to evaluate ovarian tumors. The secretory origin of this carbohydrate antigen in meiotic cells prompted further analyses of peritoneal fluid collected from gynecological surgery patients including those diagnosed with ovarian cancer. The present study demonstrates that ovarian tumor proteins separated on SDS PAGE include an antigen having a heterogeneous molecular weight (> 100 kDa) typical of glycosylated proteins. Additional studies show that peritoneal fluid from 19 patients not having cancer contain PS1 associated glycoproteins. However, of 14 cancer patients, only one had detectable levels of the carbohydrate antigen. These observations suggest that either the secretion of this glycoprotein is altered in ovarian carcinoma or that glycosidases or other proteolytic enzymes are involved in the degradation of these glycoproteins.