Bishop D K, Shelby J, Eichwald E J
Department of Medicine, University of Utah School of Medicine, Salt Lake City 84132.
Transplantation. 1992 Apr;53(4):849-57.
Modified limiting dilution analysis (LDA) techniques were used to evaluate the mobilization of antigen-stimulated helper T lymphocytes (HTL) and cytotoxic T lymphocytes (CTL) following allogeneic heterotopic cardiac transplantation. These modified LDA techniques allow a quantitative comparison of T cells that have been stimulated by antigen in vivo versus unstimulated precursor T cells of the same antigen specificity. Endothelial changes associated with mononuclear cell infiltration of the transplant were studied using endothelia-specific monoclonal antibodies and immunohistochemistry. Early (day 3) infiltration of cardiac allografts was characterized by a prevalence of donor alloantigen-specific HTL over CTL. Immunohistology revealed that the day-3 infiltrate was associated with areas of differentiated vascular endothelium, located primarily in the subepicardial region. Though donor-specific precursor HTL and CTL were present in the peripheral lymphoid tissues and blood, very few of them had been stimulated at this early time. During the latter phases of the response (days 6-9), antigen-stimulated HTL and CTL were present in the rejecting heart with CTL dominating the response. Accumulation of large numbers of donor-specific CTL in the allograft correlated with extensive inflammatory endothelial development, myocyte destruction, and loss of graft function by day 9. Stimulated HTL and CTL were detectable in peripheral lymphoid tissues at days 6 and 9. In addition, a marked increase in the number of donor-specific precursor CTL, but not precursor HTL, was observed in the lymphoid tissues at the peak of the response. Depletion of class II MHC-restricted T cells by in vivo treatment with anti-CD4 mAb eliminated HTL activity in all lymphoid compartments assessed and markedly reduced the number of CTL infiltrating the allograft. In addition, no stimulated CTL were detectable in lymphoid tissues, and the number of precursor CTL was not increased. In anti-CD4-treated recipients, cardiac allografts remained functional with minimal histological evidence of rejection for at least 21 days. Though graft-associated inflammatory endothelia were absent in anti-CD4-treated recipients at day 6, endothelial differentiation was observed in day 21 allografts in anti-CD4-treated recipients. These observations indicate that inflammatory endothelial development may precede T cell infiltration and subsequent loss of the cardiac allograft function. Thus, CD4-positive HTL are required for (1) graft-associated inflammatory endothelial development; (2) CTL activation in peripheral lymphoid tissues; (3) CTL accumulation in allografted tissues; and (4) acute cardiac allograft rejection.
采用改良的极限稀释分析（LDA）技术，评估同种异体异位心脏移植后抗原刺激的辅助性T淋巴细胞（HTL）和细胞毒性T淋巴细胞（CTL）的动员情况。这些改良的LDA技术能够对体内受抗原刺激的T细胞与具有相同抗原特异性的未受刺激的前体T细胞进行定量比较。使用内皮特异性单克隆抗体和免疫组织化学方法，研究与移植组织单核细胞浸润相关的内皮变化。心脏同种异体移植早期（第3天）的浸润特征是供体同种异体抗原特异性HTL的数量超过CTL。免疫组织学显示，第3天的浸润与主要位于心外膜下区域的分化血管内皮区域有关。尽管供体特异性前体HTL和CTL存在于外周淋巴组织和血液中，但在这个早期阶段，它们中很少有被激活的。在反应的后期阶段（第6 - 9天），抗原刺激的HTL和CTL存在于发生排斥反应的心脏中，且CTL在反应中占主导地位。到第9天时，同种异体移植中大量供体特异性CTL的积累与广泛的炎性内皮细胞发育、心肌细胞破坏以及移植物功能丧失相关。在第6天和第9天时，在外周淋巴组织中可检测到被激活的HTL和CTL。此外，在反应高峰期，在淋巴组织中观察到供体特异性前体CTL数量显著增加，而前体HTL数量未增加。通过用抗CD4单克隆抗体进行体内治疗，清除II类MHC限制性T细胞，消除了所有评估的淋巴区室中的HTL活性，并显著减少了浸润同种异体移植组织的CTL数量。此外，在淋巴组织中未检测到被激活的CTL，并且前体CTL的数量也未增加。在接受抗CD4治疗的受体中，心脏同种异体移植至少在21天内保持功能，组织学上排斥反应的证据极少。尽管在第6天时，接受抗CD4治疗的受体中不存在与移植物相关的炎性内皮细胞，但在接受抗CD4治疗的受体的第21天同种异体移植中观察到了内皮分化。这些观察结果表明，炎性内皮细胞发育可能先于T细胞浸润以及随后心脏同种异体移植功能的丧失。因此，CD4阳性的HTL对于（1）与移植物相关的炎性内皮细胞发育；（2）外周淋巴组织中CTL的激活；（3）CTL在同种异体移植组织中的积累；以及（4）急性心脏同种异体移植排斥反应是必需的。
