REJECTION MECHANISM AND IMMUNOSUPPRESSIVE STRATEGY OF SMALL BOWEL TRANSPLANTATION.

p38丝裂原活化蛋白激酶（MAPK）是一种负责转导炎症信号的应激活化酶。在CD 8 + T淋巴细胞上，p38表达与细胞毒活性相关。关于凋亡信号通路，p38被TNF-α激活，并且p38的激活可诱导凋亡。方法.行异位小肠移植（SBT）。第1组。LEW → LEW（n=3），组2。BN → LEW（n=5，未处理），组3，BN → LEW（n=3，FK 506 0.5 mg/kg，肌肉注射，连续7天）。4组BN → LEW（n=3，抗TNF-α抗体，1.0mg/kg，SBT时腹腔注射）。组织学、细胞凋亡、p38和磷酸化p38的免疫染色以及磷酸化p38的Western blot检测。结果移植后第7天，第1组的组织病理学结果显示，第2组出现中度至重度排斥反应。另一方面，第3组和第4组在移植后第7天表现出轻度至中度排斥反应。第2组移植物浸润的CD 8a/p38双阳性细胞较第3组显著增加。关于通过Mann-Whitney U检验的TUNEL阳性细胞10 HPF，第2组（9.4±3.6）中的阳性细胞多于第1组（0.7±0.6）（p=0.024）。然而，与第2组相比，第4组中的阳性细胞数量（4.3±1.5）显著减少（p=0.047）。四组间p38表达细胞数无显著性差异。磷酸化特异性p38蛋白的表达，第2组阳性细胞数多于第4组。在排斥移植物中磷酸化特异性p38的免疫印迹中，组2中检测到的免疫反应条带强于组4。结论.由于在同种异体移植排斥反应中浸润细胞主要表达磷酸化特异性p38，FK 506和抗TNF抗体联合治疗可能通过抑制p38的活化而成功。

The p38 mitogen-activated protein kinase (MAPK) is a stress-activated enzyme responsible for transducing inflammatory signals. On CD8+ T lymphocytes, p38 expression correlates with cytotoxic activity. Concerning apoptotic signaling pathways, p38 is activated by TNF-α and activation of p38 may induce apoptosis. Methods. Heterotopic small bowel transplantation (SBT) was performed. Group1. LEW → LEW (n=3), Group2. BN → LEW (n=5, no treatment), Group3, BN → LEW (n=3, FK506 0.5 mg/kg, i.m.for 7 days). Group4 BN → LEW (n=3, anti-TNF-α antibody ; 1.0mg/kg, i.p.injection at SBT). Histology, apoptosis, immunostaining of p38 and phosphospecific p38, and Western blot of phosphospecific p38 were examined. Results. The histopathologic findings of Group 1 on day 7 after transplantation, moderate to serve rejection was observed in Group 2. On the other hand, Group 3 and 4 on day 7 after transplantation showed mild to moderate rejection. The graft infiltrating CD8a/p38-double positive cells in Group 2 significantly increased compared with Group3. Concerning TUNEL-positive cells 10 HPF by Mann-Whitney U-test, there were more positive cells in Group 2 (9.4±3.6) than in Group 1 (0.7±0.6) (p=0.024). However, the number of positive cells in Group 4 (4.3±1.5) decreased significantly compared with Group 2 (p=0.047). There was no significant difference in the number of cells expressing p38 among four groups. In expression of phosphospecific p38, the numbers of positive cells in Group 2 seemed like more than that in Group 4. In the western blotting of phosphospecific p38 in rejecting allografts, immunoreactive bands in Group 2 were detected stronger than that in Group 4. Conclusions. Since the infiltrating cells at allograft rejection would predominantly express phosphospecific p38, combined FK506 and anti-TNF antibody therapy might success by suppressing the activation of p38.