THE PATTERNS OF COEXPRESSION OF TUMOR-ASSOCIATED ANTIGENS CA-19-9, TAG-72, AND DU-PAN-2 IN HUMAN PANCREATIC-CANCER

Coexpression of CA 19-9, DU-PAN-2, and TAG-72 was examined by a multil abeling immunohistochemical procedure in 31 surgically resected human pancreatic carcinomas. CA 19-9 was expressed in 74%, DU-PAN-2 in 84%, and TAG-72 in 65% of the cases. CA 19-9 and DU-PAN-2 were coexpressed in 16 cases (52%), CA 19-9 and TAG-72 in 10 cases (32%), DU-PAN-2 and TAG-72 in 8 cases (26%), and all three antigens in 10 tumors (32%). Wi th the combination of the three antibodies, all 31 tumors were labeled . However, heterogeneity in antigen expression existed and the antibod ies against CA 19-9, DU-PAN-2, and TAG-72 depicted 55%, 49%, and 35% o f the tumor cells, respectively. The average number of cells coexpress ing CA 19-9 and DU-PAN-2, CA 19-9 and TAG-72, DU-PAN-2, and TAG-72 was 22%, 11%, and 10%, respectively. Only about 3% of tumor cells coexpre ssed all three antigens, whereas 8% of tumor cells did not express any of the antigens. There was no correlation between the patterns of ant igen expression and age or sex. However, there was a tendency of reduc ed CA 19-9, DU-PAN-2, and TAG-72 expression in less differentiated tum or areas. The results show that: 1) pancreatic cancer cells coexpress two or three antigens in different proportions; and 2) although the se nsitivity for pancreatic cancer reaches 100% by all three antibodies, a remarkable heterogeneity exists and a minor fraction of tumor cells does not seem to produce any of these antigens.