O'Riordain D S, Mendez M V, O'Riordain M G, Molloy R G, Holzheimer R G, Collins K, Saporoschetz I, Mannick J A, Rodrick M L
Department of Surgery, Harvard Medical School, Brigham and Women's Hospital, Boston, Mass. 02115.
Surgery. 1993 Aug;114(2):407-14; discussion 414-5.
Among the fundamental immunologic abnormalities induced by serious traumatic or thermal injury are alterations in T cell activation, reduced lymphocyte interleukin-2 (IL-2) production, and associated depression of T lymphocyte proliferation. This study attempts to localize the cellular mechanisms underlying abnormal IL-2 production in thermal injury.
Following National Institutes of Health guidelines, 150 A/J mice were anesthetized, subjected to a 20% full-thickness scald burn injury or sham burn, and killed at intervals from 4 to 21 days later; splenocytes were harvested for in vitro studies. For measurement of IL-2 production, cells were cultured with either concanavalin A or a combination of the phorbol ester PMA, which directly activates protein kinase C, and the calcium ionophore A23187, which increases intracellular calcium. Cytokine mRNA expression was measured by Northern blot analysis and IL-2 production by bioassay.
Both IL-2 production and IL-2 mRNA expression were consistently suppressed in concanavalin A-stimulated cells from burned mice compared with sham burns. This suppression of IL-2 and IL-2 mRNA also occurred when T cells were activated with PMA and A23187, bypassing the earlier stages of the signal transduction mechanism. IL-1 beta and tumor necrosis factor-alpha mRNA expression were consistently increased in burned animals, indicating that decreased IL-2 mRNA expression was specific to IL-2 and not representative of a global decrease in cytokine mRNA expression.
These results suggest that the principal cellular abnormalities that result in altered T cell activation and IL-2 production after thermal injury lie downstream of the initiating signal transduction events and before IL-2 gene transcription.
严重创伤或热损伤所引发的基本免疫异常包括T细胞活化改变、淋巴细胞白细胞介素-2（IL-2）产生减少以及相关的T淋巴细胞增殖受抑。本研究旨在确定热损伤中IL-2产生异常的细胞机制。
按照美国国立卫生研究院的指南，对150只A/J小鼠进行麻醉，使其遭受20%的全层烫伤或假烫伤，并在4至21天后的不同时间点处死；收集脾细胞用于体外研究。为了测量IL-2的产生，将细胞与伴刀豆球蛋白A或佛波酯PMA（直接激活蛋白激酶C）和钙离子载体A23187（增加细胞内钙）的组合一起培养。通过Northern印迹分析测量细胞因子mRNA表达，并通过生物测定法测量IL-2的产生。
与假烫伤相比，烫伤小鼠经伴刀豆球蛋白A刺激的细胞中IL-2的产生和IL-2 mRNA表达均持续受到抑制。当用PMA和A23187激活T细胞，绕过信号转导机制的早期阶段时，IL-2和IL-2 mRNA的这种抑制也会发生。烫伤动物中IL-1β和肿瘤坏死因子-α mRNA表达持续增加，表明IL-2 mRNA表达降低是IL-2特有的，而非细胞因子mRNA表达普遍下降的代表。
这些结果表明，热损伤后导致T细胞活化和IL-2产生改变的主要细胞异常位于起始信号转导事件的下游和IL-2基因转录之前。
