Goldstein D R, Chang T, Sweeney S D, Kirklin J K, Thomas J M, George J F
Department of Medicine, University of Alabama at Birmingham, 35294-0007, USA.
Transplantation. 2000 Oct 15;70(7):1068-73. doi: 10.1097/00007890-200010150-00013.
Peritransplant treatment with antithymocyte serum (ATS) and posttransplantation administration of donor bone marrow or donor splenocytes results in extended skin allograft survival. In this study, we examined the molecular basis of the tolerance promoting effect of donor bone marrow (BMC) cells and splenocytes with emphasis on the role of CD8 expression on the donor cells.
(C57BL/6J x A/J)F1 mice were treated on days -1 and +2 with ATS relative to transplantation with C3H/HeJ skin. On day +7, they were infused with CD8+ BMC, CD8- BMC, CD8+ splenocytes, or CD8- splenocyte donor subpopulations isolated by magnetic or fluorescence-based sorting. In additional experiments, B10.D2(R107) mice were treated in the same manner with C57BL/6 skin and BMC or splenocytes from C57BL/6 mice in which the CD8alpha gene had been inactivated.
CD8+ donor bone marrow cells induced operational tolerance (defined as graft acceptance in the absence of chronic immunosuppression) in skin graft recipients at a dose that was reduced by 250-fold relative to unfractionated bone marrow cells (1.0x10(5) cells per recipient, median survival time (MST)=41 days vs. 2.5x10(7) cells per recipient, MST=49 days, P=0.40). Similarly, donor bone marrow cells from CD8 knockout mice did not promote graft acceptance (MST=98 days vs. animals not treated with bone marrow cells, MST=70 days, P=0.16). In contrast, the extension of graft survival by donor splenocytes did not require the presence of CD8+ donor cells because splenocytes depleted of CD8+ cells extended graft survival (MST=55 days) as well as unsorted splenocytes (44 days, P=0.2), and splenocytes from CD8 knockout animals (MST=145 days) extended graft survival at least as well as unsorted splenocytes (MST=74 days, P=0.4)
These results suggest that the prolongation of graft survival by donor bone marrow is dependent on the presence of the CD8 molecule, whereas prolongation by donor splenocytes is not. Therefore, we suggest that the prolongation of graft survival by these cell types occurs via distinct molecular mechanisms probably mediated by different cell types.
移植前用抗胸腺细胞血清（ATS）处理以及移植后给予供体骨髓或供体脾细胞可延长皮肤同种异体移植的存活时间。在本研究中，我们研究了供体骨髓（BMC）细胞和脾细胞促进耐受作用的分子基础，重点关注供体细胞上CD8表达的作用。
相对于用C3H/HeJ皮肤进行移植，（C57BL/6J×A/J）F1小鼠在移植前第-1天和移植后第+2天用ATS处理。在第+7天，给它们输注通过基于磁性或荧光的分选分离出的CD8⁺BMC、CD8⁻BMC、CD8⁺脾细胞或CD8⁻脾细胞供体亚群。在另外的实验中，B10.D2（R107）小鼠用C57BL/6皮肤以及来自CD8α基因已失活的C57BL/6小鼠的BMC或脾细胞以相同方式处理。
CD8⁺供体骨髓细胞在皮肤移植受者中诱导了操作性耐受（定义为在无慢性免疫抑制情况下的移植物接受），其剂量相对于未分级的骨髓细胞降低了250倍（每个受者1.0×10⁵个细胞，中位存活时间（MST）=41天，而每个受者2.5×10⁷个细胞，MST=49天，P=0.40）。同样，来自CD8基因敲除小鼠的供体骨髓细胞未促进移植物接受（MST=98天，而未用骨髓细胞处理的动物，MST=70天，P=0.16）。相反，供体脾细胞延长移植物存活并不需要CD8⁺供体细胞的存在，因为去除CD8⁺细胞的脾细胞延长了移植物存活时间（MST=55天），未分选的脾细胞也是如此（44天，P=0.2），并且来自CD8基因敲除动物的脾细胞（MST=145天）至少与未分选的脾细胞一样延长了移植物存活时间（MST=74天，P=0.4）。
这些结果表明，供体骨髓延长移植物存活依赖于CD8分子的存在，而供体脾细胞延长移植物存活则不依赖。因此，我们认为这些细胞类型延长移植物存活是通过可能由不同细胞类型介导的不同分子机制发生的。
