Immunohistochemical study of colorectal adenomas with monoclonal antibodies against blood group antigens (sialosyl-Le(a), Le(a), Le(b), Le(x), Le(y), A, B, and H).

We studied 40 colorectal adenomas with monoclonal antibodies against blood group antigens (sialosyl-Le(a), Le(a), Le(b), Le(x), Le(y), A, B, and H). Sialosyl-Le(a), Le(a), Le(x), and Le(y) are usually present in different compartments of the crypts of normal colorectum and can be considered markers of normal differentiation antigens (NDA). The former two antigens represent markers for differentiated colonic epithelium and the latter two, markers for "undifferentiated" crypt base epithelium. Le(b), A, B, and H are normally absent from the distal colon and rectum, but are expressed by fetal colon and carcinomas and are considered oncofetal tumor-associated antigens (OF-TAA). Individual adenomas could be characterized as to whether or not they expressed OF-TAA and NDA. Of the adenomas, 35% were OF-TAA+/NDA+, 40% were OF-TAA+/NDA-, 17.5% were OF-TAA-/NDA+, and 7.5% were OF-TAA-/NDA-. When NDA were present, they were expressed in the same compartment of the crypt as in the normal colon and rectum. In adenomas there was proliferation of the undifferentiated enterocyte marker Lex throughout the entire length of the crypt when compared with controls (p less than 0.01). Of the adenomas, 75% expressed OF-TAA, however, 35% of adenomas concomitantly expressed NDA in the same distribution as normal colon and rectum indicating that adenomas have features of both carcinoma and normal colorectum epithelium.