Cesano A, Visonneau S, Clark S C, Santoli D
Wistar Institute of Anatomy and Biology, Philadelphia, PA 19104.
J Immunol. 1993 Sep 15;151(6):2943-57.
Freshly separated PBL and two IL-2-dependent clonal T cell lines (TALL-103/2 [TCR-gamma delta+] and TALL-104 [TCR-alpha beta+]) were used to dissect, at the cellular and molecular levels, the mechanisms governing the enhancing effects of IL-12 on MHC nonrestricted cytotoxic activity. IL-12 induced cytotoxicity both in PBL and TALL cells, although less efficiently than IL-2, and the two cytokines displayed additive effects. Unlike IL-2, IL-12 failed to enhance the CD3 or CD2 redirected killing of the TALL cell lines. Analysis of the percentage of E/T conjugates induced by these cytokines showed that IL-12 could increase PBL, but not TALL cell, binding only when used in combination with IL-2. This and the failure of IL-12 to increase the expression of several adhesion molecules on PBL and TALL cells indicated no significant role for IL-12 in the binding step of the lytic interaction. We also excluded that production of TNF-alpha, IFN-gamma, or IL-2 by the IL-12-activated effectors might account for the cytotoxicity-inducing effects of this cytokine. By contrast, IL-12 was found to induce cytotoxic granule formation in PBL and TALL cells and to up-regulate the expression of their cytolytic components, including perforin, serine esterases, and TIA-1, both at the protein and mRNA levels. The costimulatory action of IL-2 and IL-12 on granulogenesis and induction of cytolytic proteins correlated well with the additive effects on cytotoxicity. Studies with cyclohexamide and actinomycin D demonstrated that TALL cells but not PBL require de novo protein synthesis for expression of serine esterases and perforin mRNA after IL-2 and/or IL-12 stimulation, and that both cytokines act directly or indirectly at the transcriptional level. Overall, these data indicate that IL-12 acts mostly at a postbinding level of the lytic interaction, involving enhanced expression of cytotoxic mediators, and that IL-2 and IL-12 use partially distinct pathways to activate the MHC nonrestricted killer function of mature T cells and resting lymphocytes.
新鲜分离的外周血淋巴细胞（PBL）以及两种依赖白细胞介素-2（IL-2）的克隆性T细胞系（TALL-103/2 [TCR-γδ+]和TALL-104 [TCR-αβ+]）被用于在细胞和分子水平剖析调控IL-12对主要组织相容性复合体（MHC）非限制性细胞毒性活性增强作用的机制。IL-12在PBL和TALL细胞中均诱导细胞毒性，尽管效率低于IL-2，且这两种细胞因子表现出相加效应。与IL-2不同，IL-12未能增强TALL细胞系的CD3或CD2介导的重定向杀伤作用。对这些细胞因子诱导的效应细胞与靶细胞（E/T）结合物百分比的分析表明，仅在与IL-2联合使用时，IL-12才能增加PBL的结合，但不能增加TALL细胞的结合。这以及IL-12未能增加PBL和TALL细胞上几种黏附分子的表达表明，IL-12在溶细胞相互作用的结合步骤中无显著作用。我们还排除了IL-12激活的效应细胞产生肿瘤坏死因子-α（TNF-α）、干扰素-γ（IFN-γ）或IL-2可能解释该细胞因子诱导细胞毒性的作用。相比之下，发现IL-12可诱导PBL和TALL细胞中细胞毒性颗粒的形成，并在蛋白质和mRNA水平上调其溶细胞成分的表达，包括穿孔素、丝氨酸酯酶和TIA-1。IL-2和IL-12对颗粒形成和溶细胞蛋白诱导的共刺激作用与对细胞毒性的相加效应密切相关。用环己酰胺和放线菌素D进行的研究表明，TALL细胞而非PBL在IL-2和/或IL-12刺激后表达丝氨酸酯酶和穿孔素mRNA需要从头合成蛋白质，且这两种细胞因子在转录水平直接或间接发挥作用。总体而言，这些数据表明，IL-12主要在溶细胞相互作用的结合后水平发挥作用，涉及细胞毒性介质表达的增强，且IL-2和IL-12利用部分不同的途径激活成熟T细胞和静息淋巴细胞的MHC非限制性杀伤功能。
