THE EFFECTS OF PERIOPERATIVE PORTAL VENOUS INOCULATION WITH DONOR LYMPHOCYTES ON RENAL ALLOGRAFT SURVIVAL IN THE RAT

Abstract

In order to investigate the in vivo functional role of the liver in the immune responses in organ transplantation, effects of perioperative portal venous p.v. administration of donor lymphocytes on renal allograft survival were tested in the rat kidney transplant model. Donor lymphocytes were prepared from BN (BN, RT1^a) or third-party DA (RT1^a) rat spleens and lymph nodes and injected p.v. or intravenously to Lewis (LEW, RT-1) hosts on the day of transplantation (day 0). Untreated LEW hosts rejected BN renal grafts at 7.8±0.6 days (n = 10). Intravenous administration of 1×10⁸ BN cells to LEW hosts on day 0 caused a slight, but not significant, prolongation of renal allograft survival (MST = 9.5±3.0 days, n = 13, NS), whereas portal venous inoculation of 1×10⁸ BN cells on day 0 remarkably prolonged renal graft survival to 22.2±5.3 (n = 10, P < 0.01). The prolongation of graft survival was antigen-specific; the administration of 1×10⁸ DA cells p.v. to LEW hosts did not prolong the survival of BN renal grafts (MST = 7.4±0.8, n = 5). Spleen cells from p.v. treated LEW hosts 10 days after transplantation had no suppressor effect on the one-way MLC reaction of normal LEW responder cells toward donor BN or thirdparty DA stimulators. On the other hand, when serum from p.v.-treated LEW hosts was added to MLC at a concentration of 3 per cent of total volume, it suppressed the MLC reaction toward donor BN cells by 71.6 per cent, but not toward third-party DA stimulators (-8.5 per cent suppression, NS). Histological examination of p.v.-treated LEW hosts at 10 days after transplantation revealed that the liver had normal lobular architecture without expansion of portal tracts and infiltration of inflamatory cells. On the other hand, the transplanted kidney demonstrated a moderate mononuclear cell infiltration around the artery without an interstitial hemorrhage. Moreover, adoptive transfer of the serum from p.v.-treated LEW rats into the virgin secondary LEW hosts significantly prolonged the graft survival of BN kidneys from 7.8 days to 18.9±5.5 days (P<0.01), but not third-party DA graft survivals (MST = 7.5±0.6 days), indicating that an antigen-specific tolerogenic factor was released into the circulation through the process of allogeneic cells in the liver.