Effect of combined treatment with FK506, FTY720, and ex vivo graft irradiation in rat small bowel transplantation: expression of mucosal addressin cell adhesion molecule-1.

We studied the effect of the combined treatment with FK506, FTY720, and ex vivo graft irradiation. Five groups of SBT animals were studied on days 3, 5, and 7 after operation (untreated, FK506, FTY720, FK506 + FTY720, FK506 + FTY720 + irradiation). Indirect immunoperoxidase staining was performed against CD4 and MAdCAM-1. The numbers of CD4 positive cells in allografts were also analyzed by flow cytometry. The graft survival was prolonged in all of the FK506- and FTY720-treated groups. SBT allografts treated by FK506 and FTY720 demonstrated less infiltration of CD4 positive cells, but the irradiation group did not show any effects on its expression. In FK506- and FTY720-treated groups, MAdCAM-1 expression on the HEVs in PPs was up-regulated, and its expression on the ECVs in the LP was down-regulated compared with other allograft groups. Irradiation did not show any effects on MAdCAM-1 expression on both HEVs in PPs and ECVs in LP. FK506 and FTY720 prevented the infiltration of CD4 positive cells, the down-regulation of MAdCAM-1 expression on HEVs in PPs, and the up-regulation of MAdCAM-1 expression on ECVs in LP during the early phase of SBT.