HIGH-ACTIVITY CARBONIC-ANHYDRASE ISOENZYME (CA-II) IN HUMAN GALLBLADDER EPITHELIUM

Acidification of bile is one of the factors that prevents calcium prec ipitation and thereby gallstone formation. Catbonic anhydrase II (CA I I) has previously been shown to be one of the key factors in the human alimentary tract that regulates the acid-base balance. We demonstrate d CA II expression in the human gallbladder epithelium using immunohis tochemical techniques, elucidated the CA II content of the epithelium by digital image analysis of the immunohistochemically stained enzyme in samples from 16 patients undergoing cholecystectomy, and correlated the results with the calcium content of the gallstones. Nine patients had symptomatic gallstone disease and seven an acalculous, histologic ally normal gallbladder. The patients were classified into two groups on the basis of the calcium content of their gallstones: no gallstones or gallstones containing no calcium (Group 1) and gallstones with 2-8 7% calcium by weight (Group 2). The immunohistochemical techniques sho wed distinct epithelial CA II-positive staining in most of the gallbla dder samples, but digital image analysis revealed distinct variations in staining intensity among them. The median staining intensity index was significantly higher in Group 1 (0.4463) than in Group 2 (0.2376; p = 0.0262). The results suggest that CA II is abundantly expressed in the normal gallbladder epithelium and that decreased expression may b e associated with the formation of calcified gallstones. These finding s are relevant to the pathogenesis of gallstone disease.-