Benihoud K, Bonardelle D, Bobé P, Kiger N
INSERM U 267, Villejuif, France.
Eur J Immunol. 1997 Feb;27(2):415-20. doi: 10.1002/eji.1830270211.
Autoimmune-prone MRL/lpr mice, homozygous for the lpr mutation, exhibit defective apoptosis and develop generalized lymphoproliferation with the accumulation of a double-negative (DN: CD4- CD8-) T cell population. The capacity of lpr T lymphocytes to effectuate Fas- and perforin-mediated cytotoxicity was investigated. Spleen and lymph nodes cells spontaneously lyse Fas- targets (thymocytes) through a Fas-mediated mechanism as a consequence of their overexpression of Fas ligand (FasL) confirmed by semiquantitative reverse transcription (RT)-PCR and immunoprecipitation analysis. This cytotoxicity was greatly increased after stimulation of the effectors by phorbol myristate acetate (PMA) + ionomycin. Under these conditions, MRL/lpr spleen and LN cells exhibited strong Fas-mediated Ca2+-independent cytotoxic activity against wild-type Fas+ (H-2 compatible or incompatible) thymocytes or lipopolysaccharide (LPS)-transformed blast cells. Such Fas-mediated cytotoxic activity was also observed with C57BL/6-lpr, but never with wild-type C57BL/6 or MLR+/+ effectors. Depletion experiments showed that the effector cells of this Fas-mediated cytotoxicity were DN T cells. This subset, which represent in vivo activated T cells, can spontaneously lyse Fas+ targets by a mechanism that does not need the interaction of the T cell receptor (TCR) with major histocompatibility complex molecule plus antigen. This lytic potential is increased by PMA + ionomycin, which sends a second activation signal to these primed T cells. Therefore, the small amounts of Fas receptor expressed on MRL/lpr tissues may account for their nonspecific autoimmune attack by DN cells. In Con A-containing medium, which allows detection of the perforin-mediated pathway against Fas targets, cytotoxic CD8+ effectors were detected that are able to kill lpr thymocytes via a Ca2+-dependent pathway. Thus, in MRL/lpr mice, these CD8+ cells could constitute potent cytotoxic effectors against cells presenting antigen to their TCR.
纯合 lpr 突变的自身免疫易感 MRL/lpr 小鼠表现出凋亡缺陷，并随着双阴性（DN：CD4-CD8-）T 细胞群体的积累而发生全身性淋巴细胞增殖。研究了 lpr T 淋巴细胞实现 Fas 和穿孔素介导的细胞毒性的能力。脾细胞和淋巴结细胞通过 Fas 介导的机制自发裂解 Fas 靶细胞（胸腺细胞），这是由于半定量逆转录（RT）-PCR 和免疫沉淀分析证实它们过度表达 Fas 配体（FasL）。在用佛波酯肉豆蔻酸酯乙酸酯（PMA）+离子霉素刺激效应细胞后，这种细胞毒性大大增加。在这些条件下，MRL/lpr 脾细胞和淋巴结细胞对野生型 Fas+（H-2 相容或不相容）胸腺细胞或脂多糖（LPS）转化的胚细胞表现出强烈的 Fas 介导的不依赖 Ca2+的细胞毒性活性。在 C57BL/6-lpr 中也观察到这种 Fas 介导的细胞毒性活性，但在野生型 C57BL/6 或 MLR+/+效应细胞中从未观察到。耗竭实验表明，这种 Fas 介导的细胞毒性的效应细胞是 DN T 细胞。这个亚群代表体内活化的 T 细胞，它可以通过一种不需要 T 细胞受体（TCR）与主要组织相容性复合体分子加抗原相互作用的机制自发裂解 Fas+靶细胞。PMA +离子霉素增加了这种裂解潜力，它向这些已致敏的 T 细胞发送第二个激活信号。因此，MRL/lpr 组织上表达的少量 Fas 受体可能解释了它们被 DN 细胞进行非特异性自身免疫攻击的原因。在含有刀豆蛋白 A 的培养基中，该培养基允许检测针对 Fas 靶细胞的穿孔素介导的途径，检测到细胞毒性 CD8+效应细胞，它们能够通过 Ca2+依赖的途径杀死 lpr 胸腺细胞。因此，在 MRL/lpr 小鼠中，这些 CD8+细胞可以构成针对向其 TCR 呈递抗原的细胞的有效细胞毒性效应细胞。
