The role of graft-resident Kupffer cells and lymphocytes of donor type during the time course after liver transplantation--a clinico-pathological study.

Although graft-resident passenger leukocytes are known to mediate acute rejection by triggering direct allorecognition, they may also act in an immunomodulatory fashion and play an important role in tolerance induction. The present study evaluated by non-isotopic in situ hybridization and immunohistochemistry if and during which time period after transplantation Kupffer cells (KC) and lymphocytes of the liver were replaced by recipient cells and if there is any correlation with the occurrence of rejection episodes and the clinical course. A successive re-population of the liver by recipient lymphocytes and KC was observed after transplantation but a smaller portion of lymphocytes and KC with donor genotype was detectable during the whole time course studied. There was no correlation between the portion of recipient-derived KC and donor-derived lymphocytes and histopathological alterations of the liver tissue. The biopsy content of KC with recipient origin has had no prognostic significance for the probability of survival, but patients with a low portion of donor lymphocytes in the liver biopsy obtained during the first week after transplantation have had a better prognosis for survival. The present results indicate that graft-resident KC and lymphocytes are potentially not the main cell types involved in tolerance induction after liver transplantation.