caa a22 4500 465763979 CHVBK 20180323111908.0 cr unu---uuuuu 170327e19900201xx s 000 0 eng 10.1007/BF00914028 doi (NATIONALLICENCE)springer-10.1007/BF00914028 Protective and inactivating effects of neutrophil myeloperoxidase on C1q activity [Elektronische Daten] [Giuliano Zabucchi, Renzo Menegazzi, Lucia Roncelli, Paolo Bertoncin, Francesco Tedesco, Pierluigi Patriarca] 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 Clr, Cls 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. Plenum Publishing Corporation, 1990 Zabucchi Giuliano Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut Menegazzi Renzo Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut Roncelli Lucia Istituto per 1 Infanzia, Trieste, Italy aut Bertoncin Paolo Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut Tedesco Francesco Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut Patriarca Pierluigi Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut Inflammation Kluwer Academic Publishers-Plenum Publishers 14/1(1990-02-01), 41-53 0360-3997 14:1<41 1990 14 10753 https://doi.org/10.1007/BF00914028 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00914028 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zabucchi Giuliano Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut NATIONALLICENCE 700 1- Menegazzi Renzo Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut NATIONALLICENCE 700 1- Roncelli Lucia Istituto per 1 Infanzia, Trieste, Italy aut NATIONALLICENCE 700 1- Bertoncin Paolo Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut NATIONALLICENCE 700 1- Tedesco Francesco Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut NATIONALLICENCE 700 1- Patriarca Pierluigi Istituto di Patologia Generale, Università di Trieste, via A. Fleming, 22-34127, Trieste, Italy aut NATIONALLICENCE 773 0- Inflammation Kluwer Academic Publishers-Plenum Publishers 14/1(1990-02-01), 41-53 0360-3997 14:1<41 1990 14 10753 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer