Immunohistologic techniques were used to study the expression of
colorectal carcinoma-associated
antigens in
colonic polyps and to compare this with expression in the normal colonic epithelium. Forty-nine
polyps were studied using
monoclonal antibodies to 16 different
blood group and
differentiation antigens and
carcinoembryonic antigen epitopes. With the Lewis(a)
antigen and the two
epitopes of CEA recognized by 3D6 and COL-4 expression in
polyp tissue was the same as that in the normal colon. Five types of alteration of
antigen expression in
polyps were seen. The
blood group antigens A, B, and Lewis(b), which are expressed only on the right side of the normal adult colon, were detected in both neoplastic and nonneoplastic
polyps from the distal colon. The
Lewis(x) antigen and the
antigen epitopes detected by the
antibodies COL-12, CA19-9, ME491, and GA73.3 showed an increased frequency of expression in all types of
polyps in comparison with the normal colonic epithelium, while H-type 2, ND4, and the
antigen epitope detected by CO29.11 showed a slightly decreased frequency of expression in
polyp tissue. The X-like
antigen which was expressed in only 7% of normal colon specimens showed increased frequency of expression in
polyp tissue with significantly greater expression in neoplastic than hyperplastic lesions (P = 0.003). The
TAG-72 antigen was detected only in
adenomas with severe dysplasia (P = 0.01), correlating well with premalignant histology. These findings have helped us clarify the variation of
antigen expression in
colonic polyps and allowed us to define which
antigens are worthy of further investigation as markers of possible malignant transformation.