Frequency of recipient-derived chimerism and relationship with acute rejection and HLA tissue typing in transplanted livers

Background. We sought to determine the extent and time course of recipient-derived chimerism after transplantation and the relationship with acute rejection episodes (ARE) and HLA typing in hepatic allograft patients. Patients and Methods. We studied 18 needle liver biopsy specimens from patients who had undergone orthotopic liver transplantation. Fluorescent in situ hybridization (FISH) analysis for X and Y chromosomes was performed in all cases with a sex mismatch. To evaluate the HLA matching, we used serological and polymerase chain reaction (PCR) methodology. Results. There was a sex mismatch between the recipients and donors in all cases. X and Y chromosome chimerism was detected in 14 of 18 (83%; 31.14 +/- 27.4) patients. Also, no statistical association was found between the presence and the extent of chimerism and clinicopathological parameters (P < .05). Conclusions. Our results suggest that chimerism was frequently seen in liver allografts, but it did not influence the occurrence of ARE, tissue compatibility, or histopathological changes in the posttransplantation period. The clinical, immunological, and histopathological relevance of chimerism remain unclear. These results may relate to the small number of patients and disproportion of chimerism-positive versus-negative cases. Further prospective studies will be required to clarify these findings in a larger population of liver transplant patients.