Patterns of Antigen Distribution in Human Carcinomas1

Ten epithelial-specific monoclonal antibodies, including monoclonal antibodies to antigens that have been used extensively in immunodiagnosis and immunotherapy experiments, were tested for reactivity with 20 human carcinomas each of the colon, lung, and breast. The antibodies tested included B72.3, OC125, and antibodies to carcinoembryonic anti gen, the 17-1A antigen, and the milk fat globule mucin antigen (epithelial membrane antigen). Striking differences in the pattern of antigen distri bution were seen, with each antibody having a fairly consistent staining pattern, which was dependent on the tumor type. Two antibodies reacted with most or all tumor specimens and, when positive, reacted homoge neously with apparently every cell in the specimen. Other antibodies consistently produced a variegated staining pattern, typically with areas of positive cells surrounded by areas of negative tumor cells. A third pattern was strong localization to the luminal edge and/or secretions of glandular tumors; this pattern was seen primarily in colon carcinomas which have more well-developed glandular structures than breast or lung carcinomas. A correlation with biochemical properties of the antigens was evident, in that mucins or mucin-related antigens generally produced variegated staining of lung and breast carcinomas and luminal edge/ secretion staining of colon carcinomas. Such differences in antigen dis tribution are likely to be a major factor in developing methods for immunodiagnosis and immunotherapy.