CD56 as a useful marker in the regenerative process of the histological progression of primary biliary cirrhosis

Objective Owing to recent contradicting results in the study of the regenerative process after hepatic injury in primary biliary cirrhosis, we investigated the use of CD56 in tissue repair during the histological progression of primary biliary cirrhosis. Methods Fifty-three specimens were classified into Ludwig's stages (1-4) as follows: 14 specimens as stage 1, 23 as stage 2, 14 as stage 3, and two as stage 4. Immunohistochemical stain was performed for CD56. The cell types expressing the marker were morphologically analyzed to determine their origin. Results In normal liver biliary epithelial cells (including the epithelium of terminal bile ducts and bile ductules), hepatocytes, and intermediate cells (features between hepatocytes and biliary cells, distributed in interface between hepatic parenchyma and portal tract) were CD56(-). In primary biliary cirrhosis specimens, biliary epithelial cells, hepatocytes, and intermediate cells were CD56(+) distributed as 10 out of 14 cases as stage 1 (71.43%), 18 out of 23 as stage 2 (78.26%), nine out of 14 as stage 3 (64.28%), and two out of two as stage 4 (100%). The total positive cases were 39 of 53 (73.58%). CD56 was expressed equally in all three types of cells. Conclusion These findings indicate that the consistent and uniform expression of CD56 in biliary epithelial cells, hepatocytes, and intermediate cells during hepatic injury in primary biliary cirrhosis is probably related to cellular damage and may be important in tissue regeneration. Furthermore, we cannot distinguish a specific cell type from the three above mentioned ones (biliary epithelial cells, hepatocytes, intermediate cells) as a putative stem cell in primary biliary cirrhosis.