Prolongation of renal allograft survival in antilymphocyte-serum-treated dogs by postoperative injection of density-gradient-fractionated donor bone marrow.

Posttransplant injection of fractionated donor bone marrow cells results in the prolonged survival of mouse skin allografts. In this investigation, we extended the study to the use of donor bone marrow fractionated by density-gradient centrifugation in a larger animal model, canine renal transplantation. Renal allografts were placed in outbred, histoincompatible dogs treated daily with rabbit or horse antilymphocyte serum (ALS) from days -6 to +7 relative to kidney transplantation on day 0. Fresh, unfractionated donor bone marrow (BM) or a bone marrow fraction (BM Fr3) produced by centrifugation in a discontinuous Percoll density gradient was intravenously infused into recipients on days +13 or +14. Alternatively, frozen/thawed (F/Th) BM or BM Fr3 was infused after storage at -80 degrees C for two weeks. BM Fr3 and unfractionated BM significantly (P less than 0.005) prolonged for median allograft function time (MFT) beyond the controls treated only with ALS (46 and 35 days vs. 18 days). The longer MFT with BM Fr3 was achieved with 20-40% of the unfractionated BM cell dose. In addition, BM Fr3-treated dogs exhibited a slower rate of loss of kidney function. F/Th BM was as effective as fresh BM in prolonging graft survival. A reduced mixed lymphocyte response to donor and third-party cells and markedly reduced responsiveness to Con A, PHA, and pokeweed mitogens at 30-45 days posttransplant suggested that animals were nonspecifically immunosuppressed during this period. By 60 days posttransplant, in two dogs treated with BM Fr3, the MLR to third-party cells, but not to donor cells, and the responsiveness to mitogens had returned to pre-ALS treatment values. Thus, treatment with ALS combined with fresh or F/Th BM that has been fractionated is an effective method for the prolongation of kidney allografts in dogs. The development of specific, long-term immunosuppression induced by fractionated bone marrow and success with F/Th BM in this canine renal allograft model suggests that application to human transplantation may be effective with fresh or F/Th BM fractions obtained from living-related or cadaveric donors.