{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T10:57:18Z","timestamp":1790593038330,"version":"4.1.0"},"reference-count":21,"publisher":"American Chemical Society (ACS)","issue":"4","license":[{"start":{"date-parts":[[2016,11,16]],"date-time":"2016-11-16T00:00:00Z","timestamp":1479254400000},"content-version":"vor","delay-in-days":989,"URL":"https:\/\/pubs.acs.org\/page\/policy\/authorchoice_termsofuse.html"}],"funder":[{"DOI":"10.13039\/501100000024","name":"Canadian Institutes of Health Research","doi-asserted-by":"publisher","award":["93647"],"award-info":[{"award-number":["93647"]}],"id":[{"id":"10.13039\/501100000024","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2014,4,21]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Amodiaquine (AQ) and clozapine (CLZ) are associated with a relatively high incidence of idiosyncratic agranulocytosis, a reaction that is suspected to involve covalent binding of reactive metabolites to neutrophils. Previous studies have shown that both AQ and CLZ are oxidized to reactive intermediates in vitro by activated neutrophils or by the combination of hydrogen peroxide and myeloperoxidase (MPO). Neutrophil activation leads to an oxidative burst with activation of NADPH oxidase and the production of hydrogen peroxide. However, the importance of this pathway in covalent binding in vivo has not been examined. In this study, we found that the binding of both AQ and CLZ to neutrophils from MPO knockout mice ex vivo decreased approximately 2-fold compared to neutrophils from wild-type mice, whereas binding to activated neutrophils from gp91 knockout (NADPH oxidase null) mice decreased 6\u20137-fold. When the AQ studies were performed in vivo, again the binding was decreased in MPO knockout mice to about 50% of the binding in wild-type mice; however, covalent binding was significant in the absence of MPO. Surprisingly, there was no significant decrease in covalent binding of AQ to neutrophils in vivo in gp91 knockout mice. In addition, there was extensive binding of AQ to many types of bone marrow cells and to peripheral lymphocytes. These results indicate that MPO is not the only neutrophil enzyme involved in the oxidation of AQ and that NADPH oxidase is not the major source of peroxide. There was also no decrease in AQ binding to neutrophils in COX-1 or COX-2 knockout mice. We were not able to readily reproduce the AQ in vivo studies with CLZ because of its acute toxicity in mice. These are the first studies to examine the enzymes involved in the bioactivation of AQ by neutrophils in vivo.<\/jats:p>","DOI":"10.1021\/tx500019u","type":"journal-article","created":{"date-parts":[[2014,3,3]],"date-time":"2014-03-03T18:46:33Z","timestamp":1393872393000},"page":"699-709","source":"Crossref","is-referenced-by-count":41,"title":["Involvement of Myeloperoxidase\nand NADPH Oxidase in\nthe Covalent Binding of Amodiaquine and Clozapine to Neutrophils:\nImplications for Drug-Induced Agranulocytosis"],"prefix":"10.1021","volume":"27","author":[{"given":"Alexandra R.","family":"Lobach","sequence":"first","affiliation":[{"name":"University of Toronto , , , ,","place":["Toronto, Ontario, Canada, M5S 3M2"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jack","family":"Uetrecht","sequence":"additional","affiliation":[{"name":"University of Toronto , , , ,","place":["Toronto, Ontario, Canada, M5S 3M2"]},{"name":"University of Toronto , , , ,","place":["Toronto, Ontario, Canada, M5S 3M2"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2014,3,3]]},"reference":[{"key":"2026092806091560900_cit1","doi-asserted-by":"crossref","first-page":"428","DOI":"10.1002\/ajh.21433","article-title":"Idiosyncratic\ndrug-induced agranulocytosis:\nPossible mechanisms and management","volume":"84","author":"Tesfa","year":"2009","journal-title":"Am. J. Hematol."},{"key":"2026092806091560900_cit2","doi-asserted-by":"crossref","first-page":"779","DOI":"10.1124\/pr.113.007450","article-title":"Idiosyncratic adverse\ndrug reactions: Current concepts","volume":"65","author":"Uetrecht","year":"2013","journal-title":"Pharmacol.\nRev."},{"key":"2026092806091560900_cit3","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/B978-0-12-398339-8.00003-3","article-title":"Animal models of idiosyncratic\ndrug reactions","volume":"63","author":"Ng","year":"2012","journal-title":"Adv. Pharmacol."},{"key":"2026092806091560900_cit4","doi-asserted-by":"crossref","first-page":"1476","DOI":"10.1016\/S0022-3565(25)12207-6","article-title":"Clozapine is oxidized\nby activated human neutrophils\nto a reactive nitrinium ion that irreversibly binds to the cells","volume":"275","author":"Liu","year":"1995","journal-title":"J. Pharmacol. Exp. Ther."},{"key":"2026092806091560900_cit5","doi-asserted-by":"crossref","first-page":"292","DOI":"10.1016\/S0022-3565(24)35100-6","article-title":"Metabolism of trimethoprim to a reactive\niminoquinone methide by activated human neutrophils and hepatic microsomes","volume":"291","author":"Lai","year":"1999","journal-title":"J. Pharmacol. Exp. Ther."},{"key":"2026092806091560900_cit6","first-page":"676","article-title":"Oxidation of a metabolite of indomethacin (desmethyldeschlorobenzoylindomethacin)\nto reactive intermediates by activated neutrophils, hypochlorus acid\nand the myeloperoxidase system","volume":"27","author":"Ju","year":"1998","journal-title":"Drug Metab.\nDispos."},{"key":"2026092806091560900_cit7","doi-asserted-by":"crossref","first-page":"3007","DOI":"10.1182\/blood.V92.9.3007","article-title":"Inside the neutrophil phagosome:\nOxidants, myeloperoxidase, and bacterial killing","volume":"92","author":"Hampton","year":"1998","journal-title":"Blood"},{"key":"2026092806091560900_cit8","doi-asserted-by":"crossref","first-page":"999","DOI":"10.1016\/S0026-895X(24)13269-5","article-title":"A comparison\nof the covalent binding of clozapine and olanzapine to human neutrophils\nin vitro and in vivo","volume":"53","author":"Gardner","year":"1998","journal-title":"Mol. Pharmacol."},{"key":"2026092806091560900_cit9","doi-asserted-by":"crossref","first-page":"1113","DOI":"10.1016\/0006-2952(95)00236-S","article-title":"The bioactivation of amodiaquine\nby human polymorphonuclear\nleucocytes in vitro: chemical mechanisms and the effects of fluorine\nsubstitution","volume":"50","author":"Tingle","year":"1995","journal-title":"Biochem. Pharmacol."},{"key":"2026092806091560900_cit10","doi-asserted-by":"crossref","first-page":"884","DOI":"10.1016\/S0022-3565(24)36494-8","article-title":"Disposition of amodiaquine\nand related\nantimalarial agents in human neutrophils: Implications for drug design","volume":"280","author":"Naisbitt","year":"1997","journal-title":"J. Pharmacol. Exp. Ther."},{"key":"2026092806091560900_cit11","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1055\/s-2000-8359","article-title":"Clozapine-induced agranulocytosis\nand hereditary polymorphisms of clozapine metabolizing enzymes: No\nassociation with myeloperoxidase and cytochrome P4502D6","volume":"33","author":"Dettling","year":"2000","journal-title":"Pharmacopsychiatry"},{"key":"2026092806091560900_cit12","doi-asserted-by":"crossref","first-page":"613","DOI":"10.1097\/01.jcp.0000144891.52858.a6","article-title":"Impact of myeloperoxidase and NADPH-oxidase polymorphisms\nin drug-induced agranulocytosis","volume":"24","author":"Mosyagin","year":"2004","journal-title":"J. Clin. Psychopharmacol."},{"key":"2026092806091560900_cit13","doi-asserted-by":"crossref","first-page":"5652","DOI":"10.4049\/jimmunol.170.11.5652","article-title":"Rac1 deletion\nin mouse neutrophils has selective effects\non neutrophils functions","volume":"170","author":"Glogauer","year":"2003","journal-title":"J. Immunol."},{"key":"2026092806091560900_cit14","doi-asserted-by":"crossref","first-page":"1421","DOI":"10.1016\/0006-2952(92)90198-R","article-title":"The mechansim of\nbioactivation and antigen formation of amodiaquine in the rat","volume":"43","author":"Harrison","year":"1992","journal-title":"Biochem. Pharmacol."},{"key":"2026092806091560900_cit15","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1017\/S1461145708009085","article-title":"Clozapine\nreverses schizophrenia-related behaviours in the metabotropic glutamate\nreceptor 5 knockout mouse: Association with N-methyl-d-aspartic\nacid receptor up-regulation","volume":"12","author":"Gray","year":"2009","journal-title":"Int. J. Neuropsychopharmacol."},{"key":"2026092806091560900_cit16","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1152\/physrev.00044.2005","article-title":"The NOX family of\nROS-generating NADPH oxidases: Physiology\nand pathophysiology","volume":"87","author":"Bedard","year":"2007","journal-title":"Physiol. Rev."},{"key":"2026092806091560900_cit17","volume-title":"Drug\nMetabolism: Chemical and Enzymatic Aspects","author":"Uetrecht","year":"2007"},{"key":"2026092806091560900_cit18","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1016\/0300-483X(93)90066-2","article-title":"Myeloperoxidase-mediated\nactivation of xenobiotics\nby human leukocytes","volume":"82","author":"Hofstra","year":"1993","journal-title":"Toxicology"},{"key":"2026092806091560900_cit19","doi-asserted-by":"crossref","first-page":"1451","DOI":"10.1016\/0006-2952(89)90184-6","article-title":"Drug-protein conjugates \u2013\nXVIII. Detection of antibodies towards the antimalarial amodiaquine\nand its quinone imine metabolite in man and the rat","volume":"38","author":"Christie","year":"1989","journal-title":"Biochem. Pharmacol."},{"key":"2026092806091560900_cit20","first-page":"335","article-title":"Immunogenicity of\namodiaquine in the rat","volume":"91","author":"Clarke","year":"1990","journal-title":"Int. Arch. Allergy Appl.\nImmunol."},{"key":"2026092806091560900_cit21","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1016\/0006-2952(88)90733-2","article-title":"Drug-protein conjugates\n\u2013 XIV. Mechanisms of formation of protein-arylating intermediates\nfrom amodiaquine, a myelotoxin and hepatotoxin in man","volume":"37","author":"Maggs","year":"1988","journal-title":"Biochem. Pharmacol."}],"container-title":["Chemical Research in Toxicology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/tx500019u","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/crtoec\/article-pdf\/27\/4\/699\/16028282\/tx500019u.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/crtoec\/article-pdf\/27\/4\/699\/16028282\/tx500019u.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T10:09:37Z","timestamp":1790590177000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/crtoec\/article\/27\/4\/699\/1501915\/Involvement-of-Myeloperoxidase-and-NADPH-Oxidase"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2014,3,3]]},"references-count":21,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2014,3,3]]},"published-print":{"date-parts":[[2014,4,21]]}},"URL":"https:\/\/doi.org\/10.1021\/tx500019u","relation":{},"ISSN":["0893-228X","1520-5010"],"issn-type":[{"value":"0893-228X","type":"print"},{"value":"1520-5010","type":"electronic"}],"subject":[],"published":{"date-parts":[[2014,3,3]]}}}