The 1,i antigens, which are precursors to blood group ABH antigens, accumulate in cancer cells, and are shed into the blood stream. The sera of breast carcinoma patients have been shown to contain increased serum i antigen concentation compared to those of patients with benign breast disease, healthy controls, and women with non-malignant diseases (p lesser than 0.001, respectively). Therefore, the increases in serum i-antigenic activities are apparently specific for malignancy. The overlap of i antigen values of breast carcinoma and benign breast disease patients precludes clinical application of the assay at this time. The development of a diagnostic assay for breast carcinoma-associated 1, i antigens may have clinical utility. To develop such and assay, 1,i active glycopeptides will be isolated from breast carcinoma tissue following proteolytic digention. The 1, i active glycopeptides will be purified by Concanavalin-A, Bio-Gel P-6, and high performance liquid chromatography (HPLC). The carbohydrate structures of the glycopeptides will be characterized by NMR and classical methods. For this purpose, the O-linked oligosaccharides will be cleaved from the glycopeptides by base borohydrate and purified by Bio-Gel P-6 filtration and HPLC. In the determination of structures of the 1, i active oligosaccharides, 1H and 13C NMR in conjunction with classical structural methods will be applied. Once a molecule is identified that is closely associated with breast carcinoma, hypbridoma-monoclonal antibodies will be produced against that structure. Glycopeptides from the breast carcinoma tissue or synthetic oligosaccharide-BSA conjugates will serve as immunogens. A non-competive enzyme immunoassay will be developed to detect the breast carcinoma-associated molecule. Sera will be screened to determine the predictive value of the test for breast carcinoma. In a given patient, serum 1, i activity will be compared to that expressed on the tumor tissue by immunoflourescence. The development of an assay with a high predictive value should be useful in screening for breast carcinoma and in monitoring for recurrence.