Woodle E S, Hussein S, Bluestone J A
Department of Surgery, University of Chicago, Illinois 60637, USA.
Transplantation. 1996 Mar 15;61(5):798-803. doi: 10.1097/00007890-199603150-00021.
The purpose of this study was to determine the short-term and long-term effects of repeated daily administration of low dose anti-CD3 monoclonal antibody (mAb) on CD4+ and CD8+ T cell number and function. Daily (7 days) administration of low doses (5 microg) of mitogenic (whole) or nonmitogenic (F(ab')2, fragments) anti-CD3 mAb resulted in depletion of CD4+ and CD8+ T cells in both lymph node and spleen that, in the case of whole mAb, persisted for several months in thymectomized animals. CD3+ cells obtained from thymectomized animals treated with whole but not F(ab')2 fragments of anti-CD3 mAb demonstrated decreased proliferation to anti-CD3 mAb in vitro (on a per cell basis as compared with control animals). Although purified CD4+ cells from animals treated with whole mAb demonstrated only slightly decreased proliferative responses to anti-CD3 mAb in vitro, purified CD8+ cells demonstrated an almost complete loss of their proliferative response. Studies in thymectomized animals demonstrated that the profound CD8+ cell hyporesponsiveness persisted for at least 5 months after anti-CD3 treatment. These effects were not observed in nonthymectomized animals, however, suggesting that recovery of CD8+ T cell function is caused by repopulation of lymphoid organs by thymic-derived CD8+ T cells. Additional studies with purified CD8+ cells from anti-CD3 mAb-treated animals indicated that the hyporesponsiveness was not caused by alterations in T cell receptor (TCR) expression. However, proliferative responses of anergic CD8+ T cells to phorbol ester and ionomycin were comparable to those of control CD8+ T cells. After in vitro stimulation, CD8+ cells from anti-CD3 treated animals did not produce interleukin (IL)-2, and although they retained their ability to upregulate IL-2 receptor expression (albeit reduced by about 50% compared with CD8+ cells from control animals), proliferative responses were not restored by addition of exogenous IL-2. In addition to IL-2 receptor expression, CD8+ cells from anti-CD3-treated animals also demonstrated an ability to upregulate CD44 and LFA-1 expression upon reexposure to anti-CD3 mAb in vitro. In conclusion, treatment with daily administration of low doses of whole or F(ab')2 fragments of anti-murine CD3 mAb induces significant T cell depletion in secondary lymphoid organs and does not seem to alter CD4+ proliferative responses in vitro, but whole mAb (and not F(ab')2 fragments) profoundly suppresses CD8+ proliferative responses. The profound hyporesponsiveness of CD8+ T cells induced by whole anti-murine CD3 mAb (1)persists for at least persists for at least several months, (2) is characterized by decreased IL-2 production and responsiveness to IL-2, and (3) recovery of CD8+ cell function is likely mediated by repopulation of lymphoid organs by thymic-derived CD8+ cells.
本研究的目的是确定每日重复给予低剂量抗CD3单克隆抗体（mAb）对CD4 +和CD8 + T细胞数量及功能的短期和长期影响。每日（7天）给予低剂量（5微克）的促有丝分裂（完整）或无促有丝分裂作用（F(ab')2片段）的抗CD3 mAb，导致淋巴结和脾脏中的CD4 +和CD8 + T细胞耗竭，对于完整mAb而言，在胸腺切除的动物中这种情况持续数月。从用抗CD3 mAb的完整片段而非F(ab')2片段处理的胸腺切除动物中获得的CD3 +细胞，在体外对抗CD3 mAb的增殖能力降低（与对照动物相比，以每个细胞为基础）。尽管用完整mAb处理的动物的纯化CD4 +细胞在体外对抗CD3 mAb的增殖反应仅略有降低，但纯化的CD8 +细胞的增殖反应几乎完全丧失。在胸腺切除动物中的研究表明，抗CD3治疗后，CD8 +细胞的深度低反应性持续至少5个月。然而，在未进行胸腺切除的动物中未观察到这些效应，这表明CD8 + T细胞功能的恢复是由胸腺来源的CD8 + T细胞对淋巴器官的重新填充引起的。对来自抗CD3 mAb处理动物的纯化CD8 +细胞的进一步研究表明，低反应性不是由T细胞受体（TCR）表达的改变引起的。然而，无反应性CD8 + T细胞对佛波酯和离子霉素的增殖反应与对照CD8 + T细胞相当。体外刺激后，来自抗CD3处理动物的CD8 +细胞不产生白细胞介素（IL）-2，并且尽管它们保留了上调IL-2受体表达的能力（尽管与对照动物的CD8 +细胞相比降低了约50%），但添加外源性IL-2并不能恢复增殖反应。除了IL-2受体表达外，来自抗CD3处理动物的CD8 +细胞在体外再次暴露于抗CD3 mAb时，也表现出上调CD44和LFA-1表达的能力。总之，每日给予低剂量的抗小鼠CD3 mAb的完整或F(ab')2片段进行治疗，可在二级淋巴器官中诱导显著的T细胞耗竭，并且似乎不会改变体外CD4 +细胞的增殖反应，但完整mAb（而非F(ab')2片段）会深度抑制CD8 +细胞的增殖反应。由完整抗小鼠CD3 mAb诱导的CD8 + T细胞的深度低反应性：（1）至少持续数月；（2）其特征在于IL-2产生减少和对IL-2的反应性降低；（3）CD8 +细胞功能的恢复可能是由胸腺来源的CD8 +细胞对淋巴器官的重新填充介导的。
