Histologic damage of lung allografts according to magnitude of acute rejection in the re-isotransplant model.

Abstract

BACKGROUND: Graft damage due to acute rejection has been reported as one of the risk factors in the chronic stage of cardiac and renal allografts. This study was designed to elucidate the histologic changes of grafts after ongoing acute allograft rejection was discontinued in models of lung re-isotransplantation. METHODS: WKAH rat lungs were orthotopically transplanted into F344 recipients. Three days (3A group) and 5 days (5A group) after the first allotransplantation, the grafts were re-isotransplanted back into the WKAH rats (3RA and 5RA groups, respectively). Five days (5I group) after the first isotransplantation, the grafts were re-isotransplanted back into the WKAH rats (5RI group). The grafts were removed 30 and 60 days after re-isotransplantation and assessed histologically. RESULTS: Typical acute allograft rejection developed in the 3A and 5A groups, and the changes were reduced after re-isotransplantation, although they remained significantly greater in the 5RA group than in the 3RA and 5RI groups. For intimal hyperplasia, the graft score 60 days after re-isotransplantation in the 5RA group was significantly higher than in the 5RI and 3RA groups. The changes in airway inflammation were significantly greater in the 5RA group than in the 3RA and 5RI groups at 60 days. Peribronchiolar fibrosis was significantly more frequent in the 5RA and 3RA groups than in the 5RI group. CONCLUSIONS: Acute rejection and airway inflammation corresponded to the magnitude of rejection before retransplantation. Significant intimal hyperplasia developed in severe acute rejection, and peribronchiolar fibrosis occurred after the first acute rejection.