Selection of carbohydrate antigens in human epithelial ovarian cancers as targets for immunotherapy: serous and mucinous tumors exhibit distinctive patterns of expression

Expression of blood group-related carbohydrate antigens was examined in frozen sections from a series of ovarian carcinomas of different histological types using an indirect immunoperoxidase technique. Antigenic specificities belonging to the O(H) and Lewis blood group families (H-1, H-2, Le(a), sLe(a), Le(x), sLe(x), Le(b) and Le(y)) or the mucin-core family (Tn, sTn and TF) were studied. A distinct difference in antigen expression between mucinous and other ovarian carcinomas (serous and endometrioid) was observed. Specifically, mucinous tumors tended to express sTn, Le(a) and sLe(a) strongly and homogeneously, whereas serous and endometrioid tumors rarely expressed these specificities and, in contrast, expressed Le(y) and H type 2 antigen strongly. When expressed in serous tumors, sTn was usually distributed in a heterogeneous pattern, whereas sTn expression in mucinous tumors was much more homogeneous. The distribution of Le(y) in serous tumors was noticeably homogeneous. H-1, Le(x), sLe(x), Le(b), TF and Tn specificities were rarely expressed in any type of ovarian carcinoma. Our results provide further support for the different histogenesis of mucinous and non-mucinous tumors and indicate alternative differentiation pathways for the 3 pathological subtypes of ovarian tumor. They also provide the basis for the choice of carbohydrate antigens for active and passive immunotherapy of ovarian carcinomas.