van Kessel K P, van Strijp J A, Verhoef J
Eijkman-Winkler Laboratory of Medical Microbiology, University of Utrecht, School of Medicine, The Netherlands.
J Immunol. 1991 Dec 1;147(11):3862-8.
Activated human neutrophils (PMN) degrade rTNF-alpha resulting in a loss of cytotoxic activity against murine L-929 cells (L cells). This inactivation is mediated through proteases released from activated PMN. Exposure of TNF to H2O2, glucose oxidase, xanthine oxidase, or myeloper-oxidase-H2O2-halide did not affect TNF cytotoxicity for L cells. Exposure to trypsin, chymotrypsin, pronase E, or elastase, however, did diminish TNF bioactivity. FMLP-stimulated PMN in the presence, but not in the absence, of cytochalasin B reduced TNF activity, whereas PMA-stimulated PMN did not affect TNF. Stimulation of PMN with opsonized bacteria also induced TNF inactivation as well as the supernatant of FMLP-stimulated cells. Addition of protease inhibitors to the FMLP-stimulated cytochalasin B-treated PMN abrogated the inactivation of TNF cytotoxicity for L cells, whereas scavengers were not protective. In addition, PMN from a chronic granulomatous disease patient also decreased TNF bioactivity. Inactivation of TNF by activated PMN correlated with granule release and not with superoxide production. Exposure of TNF to proteases and FMLP-activated PMN also resulted in a loss of reactivity with anti-TNF antibodies, as measured by ELISA, and in the formation of an approximately 10-kDa split product from the 17-kDa rTNF molecule. Partial degradation of TNF by proteases released from activated PMN may result in a diminished TNF bioactivity and thereby contribute to the regulation of local inflammatory reactions.
活化的人中性粒细胞（PMN）可降解重组肿瘤坏死因子-α（rTNF-α），导致其对小鼠L-929细胞（L细胞）的细胞毒性活性丧失。这种失活是由活化的PMN释放的蛋白酶介导的。将TNF暴露于过氧化氢、葡萄糖氧化酶、黄嘌呤氧化酶或髓过氧化物酶-H2O2-卤化物中，不会影响TNF对L细胞的细胞毒性。然而，暴露于胰蛋白酶、糜蛋白酶、链霉蛋白酶E或弹性蛋白酶中，确实会降低TNF的生物活性。在存在细胞松弛素B但不存在细胞松弛素B的情况下，经甲酰甲硫氨酸-亮氨酸-苯丙氨酸（FMLP）刺激的PMN会降低TNF活性，而经佛波酯（PMA）刺激的PMN则不会影响TNF。用调理过的细菌刺激PMN也会诱导TNF失活，以及FMLP刺激细胞的上清液。向经FMLP刺激并用细胞松弛素B处理的PMN中添加蛋白酶抑制剂，可消除TNF对L细胞细胞毒性的失活作用，而清除剂则没有保护作用。此外，来自慢性肉芽肿病患者的PMN也会降低TNF的生物活性。活化的PMN使TNF失活与颗粒释放相关，而与超氧化物产生无关。将TNF暴露于蛋白酶和FMLP活化的PMN中，还会导致通过酶联免疫吸附测定（ELISA）测量的与抗TNF抗体的反应性丧失，并导致17 kDa的rTNF分子形成约10 kDa的裂解产物。活化的PMN释放的蛋白酶对TNF的部分降解可能导致TNF生物活性降低，从而有助于调节局部炎症反应。
