Characterization of the inflammatory infiltrate in autoimmune cholangitis - A morphological and immunohistochemical study

Autoimmune cholangitis (AIC) is characterised by clinical and/or laboratory features of cholestasis, the presence of antinuclear antibodies and the lack of antimitochondrial antibodies. Histologically, changes largely identical to those found in primary biliary cirrhosis (PBC) are typically found. It is not possible to differentiate between AIC and PBC on conventional morphological grounds, and we therefore wished to find whether there is a difference between these entities in the composition of the inflammatory infiltrate leading to bile duct destruction. In liver biopsies from ten patients with confirmed AIC and ten patients with PBC the inflammatory infiltrate was characterised with antibodies against CD 3, OPD 4 CD 8, GB 7, L 26, CD 56 and CD 57. In AIC, T cells were predominant in the portal inflammatory infiltrate in nine cases. Granzyme B-positive activated cytolytic T lymphocytes were found in the bile duct epithelium in five cases. All these five cases showed inflammatory bile duct destruction. No significant differences between the immunohistochemical findings in AIC and in PBC were found. We suggest that AIC is a subgroup of PBC, antimitochondrial antibody-negative type.