OBJECTIVETo investigate the effect of allogene hepatic nonparenchymal cell (NPC) on the survival of grafted skin in mice and its underlying mechanism.

METHODSSixty-five C(3)H and fifty-eight C(57)BL/6 mice were employed in the study. Twenty C(3)H mice were used as skin donor and forty as the source of hepatic NPC. The rest five served as the stimulators of mixed lymphocyte culture (MLC) before and on the 7th, 18th, 30th, and 60th day after NPC infusion with 1 at each time point. MLC was determined and expressed as count per minute (CPM). Fifty-eight C(57)BL/6 mice were further divided into experimental (E, n = 50) and control groups (C, n = 8). The mice in C group only underwent skin grafting without NPC infusion. The mice in E group received with 2 x 10(7) NPC via caudal vein, followed by peritoneal injection of cytoxan (200 mg/kg) 48 hours later; They were grafted with skin donated from C(3)H mice 18 days after injections. The survival time of the mice in the two groups was observed. The serum levels of interleukin-4, chimera and MLC in the two groups were determined before and on 7th, 18th, 30th, 60th days after NPC infusion, and micro-chimera were aslo assessed on the 1st and 3rd day after NPC infusion. Five mice were sacrificed at each time point.

RESULTSThe survival time of skin graft in E group (70.0 +/- 17.2 day) was obviously longer than that in C group. The serum levels of IL-4, chimera in E group were increased gradually, while MLC response decreased gradually. The serum IL-4 level reached 251.5 +/- 11.0 ng/L and splenic chimera level to 26.30 +/- 1.04% on the 60th day after NPC infusion.

CONCLUSIONThe high levels of IL-4 and chimera might play important roles in inducing and maintaining immune tolerance.