Stanley J B, Gorczynski R M, Delovitch T L, Mills G B
Oncology Research, Toronto General Hospital, Ontario, Canada.
J Immunol. 1989 May 15;142(10):3546-52.
Interaction of specific ligands with TCR initiates a cascade of biochemical events which leads to expression of high affinity IL-2R and subsequent IL-2 secretion. Activation of phospholipase C (PL-C) is considered to be a key event in the initiation of this cascade. However, in addition to this PL-C-dependent pathway, PL-C-independent pathways have been hypothesized. Identification of the steps constituting these PL-C-independent pathways has been difficult because activation of PL-C and the subsequent cascade of events mask the effects of such pathways. Specific inhibitors for PL-C, or mutants defective in, the PL-C pathway would facilitate delineation of alternative activation pathways. We have identified a murine pork insulin/IAd-specific T cell hybridoma, B8P3.11, in which perturbation of the B8P3.11 TCR by either Ag in association with Ia, anti-CD3 antibodies, or a mitogenic lectin does not induce increases in myo-inositol 1,4,5-triphosphate production or cytosolic free calcium, yet it does lead to IL-2 secretion. Treatment of B8P3.11 with pertussis toxin, at concentrations which ADP-ribosylate GTP-binding proteins, inhibits IL-2 secretion. Thus, signal transduction resulting in IL-2 secretion by B8P3.11 likely involves a G protein. In contrast, TCR/ligand interaction activates the PL-C-dependent pathway in LBRM 331A5, a T cell lymphoma. Furthermore, pertussis toxin treatment, which blocks IL-2 secretion by B8P3.11, does not alter IL-2 secretion by LBRM 331A5. However, similar pertussis toxin substrates are present in both cells. Therefore, B8P3.11 T cells should help to elucidate PL-C-independent activation pathways.
特定配体与T细胞受体（TCR）的相互作用引发了一系列生化事件，这些事件导致高亲和力白细胞介素-2受体（IL-2R）的表达以及随后的IL-2分泌。磷脂酶C（PL-C）的激活被认为是这一系列反应起始的关键事件。然而，除了这条依赖PL-C的途径外，还推测存在不依赖PL-C的途径。由于PL-C的激活以及随后的一系列事件掩盖了这些途径的作用，因此确定构成这些不依赖PL-C途径的步骤一直很困难。PL-C的特异性抑制剂或PL-C途径有缺陷的突变体将有助于描绘替代激活途径。我们鉴定出一种小鼠猪胰岛素/IAd特异性T细胞杂交瘤B8P3.11，其中与Ia相关的抗原、抗CD3抗体或促有丝分裂凝集素对B8P3.11 TCR的扰动不会诱导肌醇1,4,5-三磷酸生成增加或胞质游离钙增加，但它确实会导致IL-2分泌。用百日咳毒素处理B8P3.11，在使GTP结合蛋白ADP核糖基化的浓度下，会抑制IL-2分泌。因此，导致B8P3.11分泌IL-2的信号转导可能涉及一种G蛋白。相比之下，TCR/配体相互作用在T细胞淋巴瘤LBRM 331A5中激活依赖PL-C的途径。此外，阻断B8P3.11分泌IL-2的百日咳毒素处理不会改变LBRM 331A5的IL-2分泌。然而，两种细胞中都存在类似的百日咳毒素底物。因此，B8P3.11 T细胞应有助于阐明不依赖PL-C的激活途径。
