Histopathologic comparison of anti-mitochondrial antibody-positive primary biliary cirrhosis and autoimmune cholangiopathy

Abstract

The present study aimed to investigate whether antimitochondrial antibody (AMA)-positive primary biliary cirrhosis (PBC) and AMA-negative PBC with autoantibodies differ histologically, especially with respect to infiltrating cells in portal tracts involved by chronic non-suppurative destructive cholangitis. Liver specimens were stained from 15 primary biliary cirrhosis with AMA (group 1), nine patients consistently negative for AMA but positive for antinuclear antibodies (ANA) (group 2). Group 2 showed overlapping features of PBC and autoimmune hepatitis type 1, in a pattern recently termed autoimmune cholangiopathy (AIC). We analyzed the cell population, including lymphocytes, plasma cells, large histiocytes, eosinophils and neutrophils, which had infiltrated portal tracts involved by destructive lesions. Although serum immunoglobulin M levels were higher in group 1 compared to those in group 2 ( P=0.0282), patients of both groups were broadly comparable with respect to clinical features and laboratory data. Histologically, the number of plasma cell and its percentage among inflammatory infiltrating cells in the portal tract were higher in group 2 than in group 1 ( P=0.0015, P=0.0070, respectively). The percentage of lymphocyte infiltration among inflammatory infiltrating cells in the portal tract were higher in group 1 than in group 2 ( P=0.0052). The percentage of plasma cell infiltration among inflammatory infiltrating cells in the portal tract was correlated to immunoglobulin G levels in group 2 ( r=0.949, P=0.0016). In conclusion, AMA-positive PBC and AIC showed differences in inflammatory cell population in involved portal tracts in this preliminary study.