Serological and immunochemical analysis of Lewis Y (Ley) blood group antigen expression in epithelial ovarian cancer

The expression of Le y blood group antigen in epithelial ovarian cancer tissues and cell lines has been studied using a Le y -specific monoclonal antibody (MAb 3S193). In ovarian cancer specimens, Le y was expressed in 75% of the 140 tumor specimens examined, with strong or moderate expression being observed in 56% of the samples. Seven of the II ovarian cancer cell lines studied were Le y -positive. Using immunochemical approaches, Le y epitopes were found to be expressed on 4 types of carrier molecules : CA125 ovarian cancer antigen, MUC-I mucins, lower m.w. glycoproteins and glycolipids. In cell lines, Le y was more commonly expressed on MUC-I mucin than on CA125, whereas in tumor specimens Le y was commonly found on both CA125 and MUC-I. The biochemical nature of the smaller Le y glycoproteins was not determined, but it was shown that they were not CEA and LAMP-I, known Le y carriers in some other tumor types. Glycolipids carrying Le y epitopes were detected in both ovarian cancer cell lines and tumor specimens. The presence of Le y epitopes on a number of different molecular carriers, including 2 major ovarian cancer antigens (CA125 and MUC-I), explains the high incidence of L y in ovarian cancer. The high expression of Le y in ovarian cancer and the availability of specific murine and humanized MAbs make Le y an attractive candidate target for clinical studies.