Maternal microchimerism in biliary atresia.

Background: The aim of this study was to determine the existence and extent of maternal microchimerism in the livers of biliary atresia (BA) patients.

Methods: Two series of investigations were performed based on the sex of our subjects. Subjects for series I were men, of which 6 had BA. Livers were analyzed using X and Y chromosome probes and fluorescent in situ hybridization. Subjects for series II were woman. Nine BA cases and their mothers were HLA typed (class I). Daughter livers were also tested for antibodies to maternal and other HLA. Two cases of neonatal hepatitis, 2 cases of Alagille syndrome, and 1 case of Byler syndrome acted as controls.

Results: All male BA livers were found to contain a mixture of cells with 1 and 2 X chromosomes (ie, XY or XX). All livers from male controls had only 1 X chromosome (ie, XY). All female BA subjects had varying intensities of antimaternal HLA class I (HLA-A) antibodies in their bile duct epithelium and hepatocytes (strong, 5; mild, 3; weak, 1). The liver from the female control did not display any antimaternal HLA class I antibodies (HLA-Ab).

Conclusion: Our preliminary data appear to show that maternal microchimerism is present within the livers of patients with progressive postnatal type BA. We suggest that BA could in fact be a graft-vs-host disease masquerading as an autoimmune reaction triggered by maternal microchimerism, and we intend to pursue this hypothesis further to clarify the etiology of BA.