Zabucchi G, Menegazzi R, Roncelli L, Bertoncin P, Tedesco F, Patriarca P
Istituto di Patologia Generale, Università di Trieste, Italy.
Inflammation. 1990 Feb;14(1):41-53. doi: 10.1007/BF00914028.
This study investigated the interaction between neutrophil myeloperoxidase (MPO) and the C1q component of the complement system. Using a dot-spot assay, MPO was found to bind to C1q in a dose-dependent manner. The specificity of this reaction was proved by the inhibitory effect of F(ab')2 antibodies to C1q and by the inability of MPO to bind to C1r, C1s and IgG. The interaction between MPO and C1q did not influence the enzymatic activity of the peroxidase but resulted in a more stable C1q as assessed by hemolytic assay for C1q. The protective effect of MPO on C1q did not require the presence of H2O2 in the reaction mixture nor was it inhibited by sodium azide, whereas it was abolished by heating the peroxidase. Lactoferrin and lysozyme, unlike MPO, were ineffective in protecting C1q from functional decay. Addition of H2O2 and chloride to MPO and C1q led to a complete inactivation of C1q, which could not be induced by H2O2 alone. The hypochlorite, which is known to be generated during the reaction of MPO with H2O2 and chloride, exhibited a similar inactivating effect on C1q, which was prevented by an external source of methionine.
本研究调查了中性粒细胞髓过氧化物酶（MPO）与补体系统的C1q成分之间的相互作用。采用斑点试验，发现MPO以剂量依赖性方式与C1q结合。F(ab')2抗C1q抗体的抑制作用以及MPO不能与C1r、C1s和IgG结合，证明了该反应的特异性。MPO与C1q之间的相互作用不影响过氧化物酶的酶活性，但通过C1q溶血试验评估，导致C1q更稳定。MPO对C1q的保护作用在反应混合物中不需要H2O2的存在，也不受叠氮化钠的抑制，而加热过氧化物酶则可消除这种保护作用。与MPO不同，乳铁蛋白和溶菌酶在保护C1q免受功能衰退方面无效。向MPO和C1q中添加H2O2和氯离子会导致C1q完全失活，单独的H2O2不会诱导这种失活。已知在MPO与H2O2和氯离子反应过程中产生的次氯酸盐对C1q表现出类似的失活作用，甲硫氨酸的外源可阻止这种作用。
