Lack of evidence for involvement of fetal microchimerism in pathogenesis of primary biliary cirrhosis.

Microchimerism may be involved in the etiopathogenesis of autoimmune diseases such as scleroderma. Primary biliary cirrhosis (PBC) shares some features with scleroderma, including a female predominance and a histologic picture reminiscent of chronic graft-versus-host disease. Our aim was to detect Y-chromosome-specific sequences as a marker for microchimerism in liver tissue of female patients with PBC. Liver biopsies of 105 female patients were investigated (28 patients with primary biliary cirrhosis, 25 patients with chronic hepatitis C, 6 patients with chronic hepatitis B, 9 with autoimmune hepatitis, and 37 patients with other liver diseases) by a sensitive Y-chromosome-specific polymerase chain reaction and/or fluorescence in situ hybridization (FISH) technique for the detection of the Y chromosome on a single cell level. In the liver of 9 (8.6%) female patients Y-chromosome-specific sequences were detected by PCR. Five of the patients had PBC as underlying disease, 2 had chronic hepatitis C, and 2 other liver diseases. No significant difference in the positivity rate for Y-specific sequences in females with PBC and patients with other liver diseases was found (P > 0.05). By FISH, single cells with one Y chromosome were detected in liver specimens from 3 of 21 patients suffering from PBC and from 1 of 13 patients with other liver diseases. In summary, microchimerism can be detected in livers of patients with hepatic diseases. However, in our study we found no evidence for an increased prevalence of microchimerism in the livers of patients with primary biliary cirrhosis. Our data suggest that microchimerism does not play a significant role in the development of PBC.