Heckford S E, Gelmann E P, Agnor C L, Jacobson S, Zinn S, Matis L A
J Immunol. 1986 Dec 1;137(11):3652-63.
Experiments were performed to assess the capacity of lectin (Con A), ionomycin, phorbol ester (PMA), and recombinant IL 2 to mediate proliferation as well as the expression of cell surface IL 2 receptors, two lymphokine genes, IL 2 and IFN-gamma, and the c-myc proto-oncogene in cloned T cell populations. Stimulation of T cell clones with recombinant IL 2 resulted in proliferation and sustained expression of the c-myc cellular proto-oncogene, but did not induce the expression of mRNA for the lymphokines IFN-gamma and IL 2. In contrast, stimulation of cloned T cells with lectin alone induced significant IFN-gamma and IL 2 mRNA expression, up-regulation of the number of cell surface IL 2 receptors, and transient c-myc expression. Ionomycin alone was not a sufficient signal for lymphokine mRNA induction. The phorbol ester PMA alone induced neither proliferation nor lymphokine gene expression but potentiated lectin and ionomycin-mediated signals. We also performed experiments to examine whether the T cell response to extracellular stimuli was a function of the activation state of the cell. Reexposure of 48-hr antigen-activated cloned cells to identical stimuli revealed several differences. Low but significant levels of IFN-gamma mRNA were now also reinduced in activated clones cells in response to IL 2 or PMA alone. Activated cells were refractory to reinduction of IL 2 mRNA by any stimulus, which may reflect a physiologic mechanism to limit clonal expansion after antigenic stimulation. This could be partially reversed by restimulation with lectin in the presence of cycloheximide, suggesting a role for a labile protein repressor in the down-regulation of IL 2 mRNA expression. PMA alone induced an IL 2-independent proliferative response. We demonstrate that distinct signals are required for lymphokine gene expression vs cellular proliferation in cloned T lymphocyte populations, and that the capacity of extracellular stimuli to reinduce expression of lymphokine genes or to mediate cell proliferation is altered by prior activation.
进行实验以评估凝集素（刀豆蛋白A）、离子霉素、佛波酯（PMA）和重组白细胞介素2介导克隆T细胞群体增殖以及细胞表面白细胞介素2受体、两个淋巴因子基因（白细胞介素2和干扰素-γ）和c-myc原癌基因表达的能力。用重组白细胞介素2刺激T细胞克隆导致增殖和c-myc细胞原癌基因的持续表达，但未诱导淋巴因子干扰素-γ和白细胞介素2的mRNA表达。相反，单独用凝集素刺激克隆的T细胞可诱导显著的干扰素-γ和白细胞介素2 mRNA表达、细胞表面白细胞介素2受体数量上调以及短暂的c-myc表达。单独的离子霉素不足以诱导淋巴因子mRNA表达。单独的佛波酯PMA既不诱导增殖也不诱导淋巴因子基因表达，但可增强凝集素和离子霉素介导的信号。我们还进行了实验以检查T细胞对细胞外刺激的反应是否是细胞激活状态的函数。将48小时抗原激活的克隆细胞再次暴露于相同刺激下发现了一些差异。现在，单独用白细胞介素2或PMA刺激激活的克隆细胞时，也会再次诱导出低但显著水平的干扰素-γ mRNA。激活的细胞对任何刺激再次诱导白细胞介素2 mRNA均无反应，这可能反映了一种限制抗原刺激后克隆扩增的生理机制。在存在环己酰亚胺的情况下用凝集素再次刺激可部分逆转这种情况，这表明一种不稳定的蛋白质阻遏物在白细胞介素2 mRNA表达下调中起作用。单独的PMA诱导了一种不依赖白细胞介素2的增殖反应。我们证明，在克隆的T淋巴细胞群体中，淋巴因子基因表达与细胞增殖需要不同的信号，并且细胞外刺激重新诱导淋巴因子基因表达或介导细胞增殖的能力会因先前的激活而改变。
