Comparison of cardiac rejection in heart and heart-lung concordant xenotransplantation.

Clinical observations indicate that in heart-lung grafting the heart is less frequently rejected than in heart grafting alone. In addition, our results of allograft experiments indicated that the graft survival period is longer in the former (11.8 +/- 0.8 days versus 6.6 +/- 0.5 days, p < 0.05), suggesting that the simultaneous grafting of the lung in heart-lung allografts suppressed the rejection of the grafted heart. We assessed the effect of simultaneous lung xenografting, splenectomy, and FK506 treatment on the survival of the xenografted heart in a concordant model. With Wistar rats as recipients and golden hamsters as donors, cardiac survival was compared between en bloc heart-lung and heart heterotopic xenografts. The cardiac survival of heart-lung and heart xenografts was not prolonged by FK506 treatment alone but was prolonged by splenectomy. Splenectomy plus FK506 (1.0 mg/kg/day) showed suppression of antibody production and a remarkable synergistic effect in prolongation (33.2 +/- 7.4 days versus 36.8 +/- 8.1 days) in heart-lung and heart xenografts. Simultaneous lung xenografting significantly shortened the survival period of the xenografted heart in splenectomy plus FK506 (0.5 mg/kg/day) recipients (4.8 +/- 0.8 days versus 9.0 +/- 3.5 days, p < 0.05), in contrast to the prolongation of the survival period of the grafted heart in heart-lung allografting.