Epithelial microchimerism: consistent finding in human liver transplants.

Background: Eleven liver biopsies from six male patients who received a liver transplant (LT) from female donors were examined in order to determine whether male host-derived hepatic cells were present in female grafts that exhibited minimal or important inflammatory damage.

Methods: Immunohistochemistry for epithelial cell type differentiation (anticytokeratin monoclonal antibody) and fluorescence in situ hybridization for XY chromosomes identification were performed on each slide.

Results: Host-derived hepatic cells were found in all except one transplant, with a frequency ranging from 2.3 to 25 per thousand of the total hepatocytes in the biopsy specimen. They were usually found as isolated cells scattered throughout the hepatic lobule; in one patient they were grouped into little clusters. Host-derived hepatic cells persisted throughout the histological follow up (up to 535 days after LT). Polyploidy for XY chromosome was observed.

Conclusion: Hepatocytes derived from extra-hepatic stem cells are frequently found in small numbers in human liver grafts and persist over time.