The effects of perioperative portal venous inoculation with donor lymphocytes on renal allograft survival in the rat. II. Phenotypic and functional analyses of graft-infiltrating cells

Phenotype, donor-specific cytolytic activity, and helper activity to release cytokines of cells infiltrating within renal allografts of hosts rendered unresponsive by perioperative administration of donor lymphocytes via the portal vein (p.v.) were investigated in order to analyze the mechanism of prolongation of allograft survival. Graft-infiltrating cells (GIC) were obtained from Lewis (LEW, RT-1l) hosts inoculated perioperatively with 1 x 10(8) donor Brown-Norway (BN, RT-1n) lymphocytes p.v., a group that displays prolonged renal allograft survival (MST: 22.2 +/- 5.3 days, n = 10) compared with an uninoculated control group (MST: 7.8 +/- 0.6 days, n = 10, P less than 0.01). The percentages of cytotoxic/suppressor T cells (OX-8+) and Ia-positive cells (OX-6+) in GIC (23.1 +/- 4.4% and 9.0 +/- 2.0%, respectively) and in spleen cells (7.5 +/- 2.6% and 8.5 +/- 1.1%, respectively) from p.v.-inoculated LEW hosts on day 6 postgrafting were significantly lower than those of uninoculated control recipients (GIC: OX-8; 39.4 +/- 8.2%, OX-6; 23.0 +/- 1.9%. SP cell: OX-8; 21.6 +/- 9.9%, OX-6; 12.7 +/- 0.4%, P less than 0.05). Cytolytic activity of GIC from tolerant hosts on day 6 postgrafting toward donor blastoid lymphocytes was significantly decreased (19.0 +/- 1.2% at E/T = 50), compared with that from control allografts during ongoing rejection (51.5 +/- 5.3%, P less than 0.01). The amounts of in vitro cytokine production of GIC from tolerant hosts after mitogen stimulation were remarkably decreased (IL-2: 8.7 +/- 1.4 U/ml, IL-3: 15.4 +/- 0.6 U/ml, and BSF-2: 24.6 +/- 3.5 U/ml) than those of uninoculated control hosts during ongoing rejection (IL-2: 19.6 +/- 2.9 U/ml, IL-3: 22.2 +/- 2.7 U/ml, and BSF-2: 67.5 +/- 13.2 U/ml, P less than 0.05). These results demonstrated that activation of both Tc cells and Th cells was inhibited in the spleen and in situ in renal allografts following administration of donor lymphocytes through the portal vein.