Blood-group antigen expression during pancreatic cancer induction in hamsters

The expression of blood group-related and tumor-associated antigens was examined in pancreatic adenocarcinomas and in the normal pancreas of hamsters to determine if this expression correlated with the host blood group and/or stage of carcinogenicity, respectively. Pancreatic tumors were induced by 4 weekly treatments of hamsters with N-nitrosobis(2-oxopropyl)amine (BOP) and analyzed immunohistochemically during different stages of tumor progression with polyclonal antibodies (PoAbs) and monoclonal antibodies (MoAbs) against A, B, O and Lewis (Le) isoantigens, including X, Y and CA 19-9 monosialoganglioside (gastrointestinal cancer antigen, GICA), as well as with PoAbs detecting human carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP) and the beta-subunit of human chronic gonadotropin (beta-HCG). The red blood cells of both control and tumor-bearing hamsters expressed AB and Le(a+b+)-like blood group types, as detected by polyvalent antisera. However, none of the MoAbs reacted with the hamster red blood cells. In the pancreas, all PoAbs against blood group antigens reacted with hyperplastic ducts and ductules at very early stages of carcinogenesis, as well as with neoplastic lesions, but not with normal pancreatic cells, except for the acinar cells, which were stained with PoAb-B, PoAb-Lea and PoAb-Leb. None of the MoAbs showed any affinity for the normal pancreatic cells; however, they reacted to various degrees with induced hyperplastic and neoplastic tissue. Reactivities of several MoAbs with malignant cells were greater than those with hyperplastic lesions: MoAb-B was highly reactive with all induced lesions, MoAb-A less reactive, and MoAb-H and MoAb-Ley (which has 6 sugar chains) detected only some cancer cells. Neither of the two MoAb-Lex (with 5 carbohydrate chains) reacted with carcinoma cells, although they did bind to a few hyperplastic cells. Neither MoAb-Lea and MoAb CA 19-9, nor PoAbs against CEA, AFP and beta-HCG, reacted with any normal, hyperplastic or malignant cells. These results demonstrate the differential reactivity of these PoAbs and MoAbs in normal and malignant pancreatic tissue and show that blood group antigens, especially the B isoantigens, are specific markers for induced pancreatic duct tumors in hamsters.