Comparative study of immunological tolerance in the liver transplantation from cadaver and living donor

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Microchimerism has been suggested to play an important role in the long-term acceptance of allogenic organ grafts by transplant patients and for the maintenance of a state of donor-specific low responsiveness. In order to elucidate the kinetics of the development of chimerism we have performed a follow-up analysis in patients with living-related liver transplantation (LRLTx). Blood samples obtained during the first 6 months and at 18 months post-transplant and slin biopsies taken at one month were analysed for the presence of donor cells by PCR using donor-specific HLA-DRB1 primer pairs or primers for a Y chromosome-specific sequence. Furthermore long-term patients more than 2 years after LRLTx were studied at two different time points. In the follow-up studies donor cells could be demonstrated in the blood of all patients immediately after transplantation. After a gradual decline all patients became chimerism negative for several weeks or months. At 6 months, however, 63% of them and … More at 18 months in 66% of them donor cells had reappeared. This biphasic pattern in the development of chimerism is proposed to reflect the occurrence of different donor-derived cell populations in the recipients. The cell population of cells occurring with the second wave of chimerism is likely to have been generated by donor-derived cells with stem cell potential located in the graft or in the hematopoetic organs of the recipient after emigration from the graft. The pediatric patient population studied here received haplo-identical graft from one of their parents. Thus the degree of histocompatibility is much better than in most other liver grafted patients receiving organs from cadaveric donors matched only for organ size and ABO blood groups but not for HLA antigens. Despite this difference, the incidence of chimerism was very similar to that found in recipients of cadaveric organs. Furthermore, we did not find a clear correlation between the development of detectable chimerism in skin or blood and the clinical course or the requirement for immunosuppressions. Less