After liver transplantation, the release of donor leukocytes into the host and the uptake of host leukocytes by the graft is one of the earliest immunologic interactions between donor and host. Using three-color flow cytometry, these interactions were investigated in eight patients from 5 min-24 h after receiving HLA unmatched liver grafts. Five minutes after reperfusion, 5.0 YO * 1.4 YO of all blood leukocytes in the host were of donor origin, decreasing to 1.1 % 0.8% after 24 h. Donor granulocytes preferentially disappeared from the host circulation, whereas no differences were found between NK-cells and various B-and T cell subpopulations. Furthermore, host granulocytes were preferentially retained in the donor liver. Thus, despite extensive pre-operative perfusion, more than lo9 donor leukocytes quickly leave the liver graft while host granulocytes preferentially accumulate there. A better understanding of the molecular mechanisms mediating these early interactions might help to develop new strategies for diagnosis and therapy of liver graft rejection.

After liver transplantation, the release of donor leukocytes into the host and the uptake of host leukocytes by the graft is one of the earliest immunologic interactions between donor and host. Using three-color flow cytometry, these interactions were investigated in eight patients from 5 min-24 h after receiving HLA unmatched liver grafts. Five minutes after reperfusion, 5.0 YO * 1.4 YO of all blood leukocytes in the host were of donor origin, decreasing to 1.1 % 0.8% after 24 h. Donor granulocytes preferentially disappeared from the host circulation, whereas no differences were found between NK-cells and various B-and T cell subpopulations. Furthermore, host granulocytes were preferentially retained in the donor liver. Thus, despite extensive pre-operative perfusion, more than lo9 donor leukocytes quickly leave the liver graft while host granulocytes preferentially accumulate there. A better understanding of the molecular mechanisms mediating these early interactions might help to develop new strategies for diagnosis and therapy of liver graft rejection.