Biffl W L, Moore E E, Moore F A, Barnett C C, Carl V S, Peterson V N
Department of Surgery, Denver General Hospital, USA.
Arch Surg. 1996 Jan;131(1):24-9; discussion 29-30. doi: 10.1001/archsurg.1996.01430130026005.
Neutrophil (PMN) apoptosis promotes the phagocytosis of PMNs without inciting an inflammatory response or local cytotoxic effect. This is important in the normal resolution of inflammatory processes and the control of tissue injury. Conversely, a delay in PMN apoptosis may facilitate PMN-mediated organ dysfunction by extending PMN functional integrity at an inflammatory site. Elevated circulating and tissue levels of interleukin-6 (IL-6) have been associated with postinjury organ dysfunction, and IL-6 appears to augment PMN cytotoxic functions. Therefore, we hypothesized that IL-6 delays PMN apoptosis, thereby enhancing PMN-mediated cytotoxicity.
Neutrophils isolated from healthy human donors were incubated for 24 hours in enriched RPMI 1640 cell culture medium at 37 degrees C in 5% carbon dioxide. Subgroups were incubated with IL-6, heat-denatured IL-6, or buffer alone. Apoptosis was assessed morphologically using acridine orange-ethidium bromide stain, and biochemically by DNA gel electrophoresis. Functional capacity of PMNs was assessed by superoxide generation after activation with phorbol myristate acetate or platelet-activating factor plus formyl-methionyl-leucyl-phenylalanine.
Treatment with IL-6 resulted in a greater population of surviving (nonapopototic) PMNs after 24 hours. In addition, the IL-6-treated population produced more superoxide after 24 hours than did the untreated or heat-denature IL-6-treated groups, after either activating stimulus.
Interleukin-6 delays PMN apoptosis, resulting in a larger population of surviving PMNs with a greater collective capacity for superoxide production. This could potentially facilitate PMN-mediated tissue injury and may be a mechanism whereby IL-6 contributes to organ dysfunction.
中性粒细胞（PMN）凋亡可促进PMN的吞噬作用，而不会引发炎症反应或局部细胞毒性作用。这在炎症过程的正常消退和组织损伤的控制中很重要。相反，PMN凋亡延迟可能会通过延长PMN在炎症部位的功能完整性而促进PMN介导的器官功能障碍。循环和组织中白细胞介素-6（IL-6）水平升高与损伤后器官功能障碍有关，并且IL-6似乎会增强PMN的细胞毒性功能。因此，我们推测IL-6会延迟PMN凋亡，从而增强PMN介导的细胞毒性。
从健康人类供体中分离出的中性粒细胞，在富含RPMI 1640的细胞培养基中于37℃、5%二氧化碳条件下孵育24小时。各亚组分别与IL-6、热变性IL-6或单独的缓冲液孵育。使用吖啶橙-溴化乙锭染色通过形态学评估凋亡，并通过DNA凝胶电泳进行生化评估。在用佛波酯肉豆蔻酸酯或血小板活化因子加甲酰甲硫氨酰亮氨酰苯丙氨酸激活后，通过超氧化物生成评估PMN的功能能力。
用IL-6处理24小时后，存活（未凋亡）的PMN数量更多。此外，在两种激活刺激后，经IL-6处理的细胞群体在24小时后产生的超氧化物比未处理或经热变性IL-6处理的组更多。
白细胞介素-6延迟PMN凋亡，导致存活的PMN数量增加，其产生超氧化物的集体能力更强。这可能会促进PMN介导的组织损伤，并且可能是IL-6导致器官功能障碍的一种机制。
