GRAFT-versus-host disease (GVHD), in which immunocompetent cells in the graft react against the recipient, has been one of the concerns after small bowel transplantation, because of the large amount of lymphocytes in gut-associated lymphoid tissue (GALT) and mesenteric lymph nodes. In rodent experiments, GVHD has been extensively studied using convenient unidirectional transplantation from parent strains to F1 hybrids.1 However, in fully allogeneic transplantation and large animal experiments, rejection and not GVHD has been the dominant phenomenon. We found that smail bowel transplantation from Lewis to Brown Norway rats induced fatal GVHD when transient immunosuppression with FK 506 was employed, similar to the study shown with cyclosporine (CyA).2
We had previously concentrated on recipient lymphoid trafficking after small bowel transplantation and have shown that most of the lymphoid tissues in small bowel allograft are replaced by the recipient hematolymphoid cells.3 In the current study, we focused on the donor lymphoid tissues implanted with the graft.
The fate of the donor lymphoid cells in the recipient and its relationship to the development of GVHD was examined.