| Purpose:To investigate the expression and role of costimulatory molecular B7-1 and B7-2 in rat liver during ischemia/reperfusion and the relation to liver injury.Methods:50 male Wistar rats were divided randomly into 2 groups (n = 25):sham -operated control group(S) and ischemia/reperfusion group(R).Every group were divided into 5 subgroups(n=5) according as 0 hour,24 hours,48 hours,72 hours and 96 hours after reperfusion.To induce hepatic warm ischemia in a rat model,both portal vein and hepatic artery entering the left-lateral and median lobes were occluded by clamping for 45 minutes,and then reperfused respectively for 0 hour,24 hours,48 hours,72 hours and 96 hours.At the end of reperfusion,the levels of B7-1 and B7-2 in liver sinusoidal endothelial cells of each subgroup were detected with flow cytometry.Results:Expressions of B7-1 and B7-2 protein were at very low levels in the liver tissues from sham-operated control rats or 45 minutes ischemia with 0 hour reperfusion rats。Both B7-1 and B7-2 expressions were enhanced at protein levels after warm ischemia/reperfusion.B7-2 protein is expressed at earlier time points than B7-1.In the rat liver ischemia/reperfusion model,strong expression of B7-2 was examed at 24 hours reperfusion model,whereas B7-1 at 72 hours.Conclusions:Up-regulation of costimulatory moiecular B7-1 and B7-2 elucidates the mechanism of relationship between ischemia/reperfusion injury and acute rejection;B7-1 and B7-2 may have functionally distinct roles in costimulation.B7-2 is important in mediating initial T cell activation and B7-2 is important in perpetuation of the immune response. |
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