IDENTIFICATION OF A MEIOTICALLY EXPRESSED CARBOHYDRATE ANTIGEN IN OVARIAN-CARCINOMA .2. ASSOCIATION WITH PROTEINS IN TUMORS AND PERITONEAL-FLUID

A monoclonal antibody developed against a meiotically expressed porcin e oocyte carbohydrate antigen has been shown to recognize an antigen i n 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 huma n, a few cells may remain in ovarian crypts. Because the majority of o varian carcinomas are thought to be derived from the OSE cells in agin g women the PSI antibody has been used to evaluate ovarian tumors. The secretory origin of this carbohydrate antigen in meiotic cells prompt ed further analyses of peritoneal fluid collected from gynecological s urgery patients including those diagnosed with ovarian cancer. The pre sent study demonstrates that ovarian tumor proteins separated on SDS P AGE include an antigen having a heterogeneous molecular weight (>100kD a) typical of glycosylated proteins. Additional studies show that peri toneal fluid from 19 patients not having cancer contain PSI associated glycoproteins. However, of 14 cancer patients, only one had detectabl e levels of the carbohydrate antigen. These observations suggest that either the secretion of this glycoprotein is altered in ovarian carcin oma or that glycosidases or other proteolytic enzymes are involved in the degradation of these glycoproteins.