Blood group and blood‐group‐related antigens in normal pancreas and pancreas cancer: Enhanced expression of precursor type 1, Tn and Sialyl‐Tn in pancreas cancer

Abstract
Expression of blood‐group antigens A, B, Lea, sialyl‐Lea(sLea), Leb, Lex, Ley, precursor type 1, Tn and sialyl‐Tn (sTn) was examined in non‐neoplastic pancreas (n = 37) and pancreas cancer (n = 21) using mouse monoclonal antibodies (MAbs). Immunohistochemical assays were performed on sections of paraffin‐embedded tissues using the avidin‐biotin complex method. In normal pancreas, antibodies detecting Lea, sLeaand Tn reacted with ductal epithelium, and antibodies detecting A and B reacted with acini and ducts, independently of secretor status. Lexwas weakly expressed in ducts and acini, and sTn could not be detected in normal pancreas. Expression of Leb, Leyand precursor type 1 was regulated by secretor status: Leband Leywere expressed in ducts of secretor and Lea‐b−individuals, but not in ducts of non‐secretors; precursor type I was weakly expressed in acini and ducts of non‐secretors and Lea‐b−individuals, and was absent in acini and ducts of secretors. The following alterations in the expression of blood‐group antigens were observed in pancreas cancer: (1) enhanced expression of Lex, Tn and sTn; (2) enhanced expression of precursor type I independently of secretor status; (3) loss of regulation of Lebby the secretor gene; (4) decreased expression of Ley. The weak expression of precursor type 1, Tn and sTn in non‐neoplastic pancreas, and their stronger expression in pancreas cancer, suggests that up‐regulation of their expression is associated with malignant transformation of pancreatic duct cells.