Three mouse IgG1 monoclonal antibodies (MoAbs) reactive predominantly with cytoplasmic antigens of mucinous type ovarian tumors were produced. OM-A MoAb was reactive with 11 of 14 mucinous type and two of three endometrioid type ovarian tumors, although only a minor population of the tumor cells was positive in the latter type. This MoAb was not reactive with serous type, clear cell type, or other types of ovarian tumors, nor with various types of uterine carcinoma. Normal adult and fetal tissues of female genital organs were not positive with this MoAb. Among nongynecological carcinomas, three of six metastatic tumors to the ovary from the gastrointestinal tract, one of five gastric carcinomas, and one of eight lung adenocarcinomas were positive. As for normal adult and fetal tissues of nongynecological origin, epithelium of the normal stomach, small bowel, and bronchus as well as epithelium of fetal small and large bowel and secretory products were weakly positive. Thus, this MoAb showed a selected specificity against mucinous and endometrioid types of ovarian tumors.

OM-B MoAb showed a broader specificity than OM-A, reacting with all mucinous type, two of three endometrioid type, and three of 16 serous type ovarian tumors, but not with clear cell type tumors. Adenoma type, but not squamous type, cervical carcinomas and one-half of endometrial carcinomas were positive. This antigen is present in cervical mucosa, but not in ovary or endometrium. OM-C MoAb showed a specificity similar to, but broader than that of, OM-B; i.e., 11 of 14 mucinous type, two of three endometrioid type, nine of 16 serous type, and one of nine clear cell type ovarian tumors were positive. It is reactive with adenoma type uterine carcinoma and normal mucosa of the uterine cervix and with normal surface epithelium of the oviduct. Among nongynecological tumors, OM-B antigen was present in metastatic tumors to the ovary as well as in gastric and pancreatic carcinomas, while OM-C was in metastatic tumors to the ovary and gastric and colonic carcinomas.

Thus, the serological analysis showed that these three MoAbs showed selective specificities to mucinous and endometrioid types of ovarian tumors. Preliminary characterization of these three OM antigens suggested that these are distinct from carcinoembryonic antigen or ABH blood group-related antigens.

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This work was supported in part by a Grant-in-Aid from the Ministry of Health and Welfare for the Comprehensive 10-Year Strategy for Cancer Control; a Grant-in-Aid for Cancer Research from the Ministry of Education, Science, and Culture, Japan; and a grant from the Cancer Research Institute, Inc., New York, NY.

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