EXPRESSION OF COSTIMULATORY FACTOR B7-2 ON THE INTRAHEPATIC BILE-DUCTS IN PRIMARY BILIARY-CIRRHOSIS AND PRIMARY SCLEROSING CHOLANGITIS - ANIMMUNOHISTOCHEMICAL STUDY

Co-stimulatory factors E7-1 (CD80) and B7-2 (CD86) and their ligands, including CD28, are important for the efficient presentation and persi stence of an antigen-specific immune reaction, Hitherto, there has bee n a paucity of data on the roles of such co-stimulatory factors in imm une-mediated biliary diseases. In this investigation, the hepatic immu nohistochemical expression of B7-1 and B7-2 has been studied, with emp hasis on intrahepatic biliary epithelia, using wedge biopsies from 22 patients with primary biliary cirrhosis (PBC), seven with primary scle rosing cholagitis (PSC), and, as controls, eight cases of extrahepatic biliary obstruction, eight of chronic viral hepatitis C, and three hi stologically normal livers. In 10/22 (45 per cent) patients with PBC a nd 3/7 (43 per cent) patients with PSC, B7-2, but not B7-1, was expres sed on the epithelial cells of small intrahepatic bile ducts and bile ductules. This expression was manifest as diffuse but variable cytopla smic staining. Such B7-2-positive bile ducts were not seen in controls . Positive staining was found only in the early stage of PBC and PSC, In PBC and PSC, almost all lymphocytes in the portal tracts, including those around the damaged bile ducts, were positive for CD28, a ligand of B7-2, These results suggest that B7-2 expression on biliary epithe lial cells is involved in antigen presentation and perhaps in bile duc t destruction in PSC and PBC, (C) 1998 John Wiley & Sons, Ltd.