An immunohistochemical study of the distribution of blood group substances and related antigens in primary colorectal carcinomas and metastatic lymph node and liver lesions, using monoclonal antibodies against A, B, H type 2, Le(a), and Le(x) antigens.

Using indirect immunoperoxidase staining, we examined the distribution of blood group substances and related antigens, including Le(a), A, B, H type 2, and Le(x), in 87 carcinomas and 42 normal mucosal specimens of colon and rectum, as well as in metastatic lesions of 32 lymph nodes and 9 liver specimens. The compatible expression rate of A/B/H type 2 antigens was 33.3% (3/9) in proximal normal colon, but only 6.1% (2/33) in distal normal colon. Compatible expression was observed in 14 of 25 carcinomas in the proximal colon (56.0%), but these antigens in distal colon cancers reappeared with a high positive rate, 62.9% (39/62). The rate of H type 2 accumulation with the deletion of A and/or B antigens was 6.9% (6/87). Incompatible expression was not observed in colorectal cancer. Le(a) and Le(x) antigens were expressed in normal mucosa and primary carcinoma throughout the colon. Le(a) and Le(x) in primary carcinoma that showed A/B deletion with/without H type 2 accumulation was expressed more than in carcinoma with A/B/H type 2 compatible expression (88.2% vs 71.7% for Le(a); 94.1% vs 88.7% for Le(x), respectively). In 16 of 32 patients (50.0%), A/B/H type 2 antigen expression in metastatic lesions had disappeared or was decreased compared with that in primary carcinoma, followed by metastasis to regional lymph nodes. These results suggested that: (a) A/B/H type 2 blood group substances in the distal colon behave as tumor-associated antigens in colorectal carcinoma. (b) Most frequently, A/B/H type 2 antigens expressed in primary carcinoma were weakened or had disappeared in metastatic lymph nodes. Further investigation of the biological function of carbohydrate chains, such as those of blood group substances and related antigens on cancer cell surfaces may lead to a solution of the problem of the metastatic behavior of tumor cells.