Bomalaski J S, Baker D G, Brophy L, Resurreccion N V, Spilberg I, Muniain M, Clark M A
Veterans Administration Medical Center, Medical College of Pennsylvania, Philadelphia 19104.
J Immunol. 1989 Jun 1;142(11):3957-62.
We have recently isolated a human phospholipase A2-activating protein (PLAP) that shares antigenic and biochemical similarities with melittin, a well characterized bee venom phospholipase-stimulatory peptide. To explore the potential mechanisms of action of PLAP that extend beyond its effects on eicosanoid synthesis, we examined its effects on the release of human neutrophil lysosomal enzymes and superoxide, and on RBC hemolysis. These results were compared to the effects of melittin, which has been reported to induce enzyme release and hemolysis. We also examined the effects of PLAP on neutrophil aggregation and chemotaxis. PLAP induced neutrophils to release beta-glucuronidase and metalloproteinase enzyme activities as well as produce superoxide ion in both a dose- and time-dependent manner. Eicosanoid synthesis inhibitors did not abrogate these responses. PLAP induced release of arachidonic acid metabolites, but this response could be abrogated by eicosanoid synthesis inhibitors. PLAP also induced neutrophil aggregation and chemokinesis, but not chemotaxis. Concentrations of PLAP that induced these responses did not induce cellular toxicity as determined by light and electron microscopy, lactic dehydrogenase release, trypan blue dye exclusion, and RBC hemolysis. In contrast, prolonged incubation with higher concentrations of PLAP induced cell death that was similar to that observed with melittin. These findings suggest that the mechanisms of action of PLAP extend beyond the eicosanoid synthetic pathway, and that disordered regulation of PLAP may be responsible, at least in part, for chronic immune and inflammatory states.
我们最近分离出一种人磷脂酶A2激活蛋白（PLAP），它与蜂毒明肽在抗原性和生化特性上有相似之处，蜂毒明肽是一种特性明确的蜂毒磷脂酶刺激肽。为了探究PLAP作用的潜在机制，这些机制超出了其对类花生酸合成的影响，我们检测了它对人中性粒细胞溶酶体酶释放、超氧化物释放以及对红细胞溶血的影响。将这些结果与蜂毒明肽的影响进行比较，据报道蜂毒明肽可诱导酶释放和溶血。我们还检测了PLAP对中性粒细胞聚集和趋化性的影响。PLAP以剂量和时间依赖性方式诱导中性粒细胞释放β-葡萄糖醛酸酶和金属蛋白酶活性，并产生超氧离子。类花生酸合成抑制剂不能消除这些反应。PLAP诱导花生四烯酸代谢产物的释放，但这种反应可被类花生酸合成抑制剂消除。PLAP还诱导中性粒细胞聚集和细胞运动，但不诱导趋化性。通过光学显微镜和电子显微镜、乳酸脱氢酶释放、台盼蓝染料排斥试验以及红细胞溶血试验确定，诱导这些反应的PLAP浓度不会诱导细胞毒性。相反，用更高浓度的PLAP长时间孵育会诱导细胞死亡，这与用蜂毒明肽观察到的情况相似。这些发现表明，PLAP的作用机制超出了类花生酸合成途径，并且PLAP调节紊乱可能至少部分地导致慢性免疫和炎症状态。
