[Characterization of inflammatory infiltrates in autoimmune cholangitis: an immunohistochemical study]

Autoimmune cholangitis is clinically characterized by cholestasis and serologically by the presence of antinuclear antibodies (ANA) and a lack of antimitochondrial antibodies (AMA). Morphologic characteristics are non suppurative bile duct destruction (NSBDD), ductopenia and occasionally granulomas. The aim of the study was to characterize the inflammatory infiltrate to find about the possible mechanism of bile duct destruction in AIC. Liver biopsy material of ten patients (9 female/1 male, mean age of 45,5 a) with the clinical and serologic features of AIC were evaluated morphologically for the presence of NSBDD, ductopenia and granulomas. The inflammatory infiltrate was characterized immunohistochemically using Ab against CD3 (pan T lymphocytes), OPD 4 (helper T lymphocytes and memory T lymphocytes), CD8 (cytotoxic T lymphocytes), GB4 (activated cytotoxic T lymphocytes), L26 (pan B lymphocytes), CD56 and CD57 (NK/K cells). Lymphocyte subsets were investigated with regard to quantity and distribution within liver tissue. For control ten cases of PBC were also investigated simultaneously. NSBDD was found in five, granulomas in three cases. Portal inflammation was seen in all cases. In 9 cases T cells outweighed B cells. GB4 positive activated cytotoxic T lymphocytes were found within bile duct epithelium in five cases. All these cases showed associated NSBDD. NK/K cells were seen infrequently. Similar findings were observed in the ten cases of PBC. We therefore conclude that bile duct destruction in AIC is mediated by activated cytotoxic T lymphocytes. AIC cannot be differentiated from PBC histologically or by immunomorphology.