The neutrophil enzyme myeloperoxidase uses H2O2 to oxidize chloride, bromide, iodide and thiocyanate to their respective hypohalous acids. Chloride is considered to be the physiological substrate. However, a detailed kinetic study of its substrate preference has not been undertaken. Our aim was to establish whether myeloperoxidase oxidizes thiocyanate in the presence of chloride at physiologica...

We have examined the effect of the myeloperoxidase-hydrogen peroxide-halide system and of activated human neutrophils on the ability of serum alpha 1-protease inhibitor (alpha 1-PI) to bind and inhibit porcine pancreatic elastase. Exposure to the isolated myeloperoxidase system resulted in nearly complete inactivation of alpha 1-PI. Inactivation was rapid (10 to 20 s); required active myelopero...

Mice were injected intravenously with Candida albicans blastospores to establish chronic renal infection. Seventy-five percent of the animals inoculated with 10(6) blastospores died as a consequence of infection during the subsequent 60 days of observation. Intraperitoneal administration of 10 mU of partially purified human myeloperoxidase 1 day after injection of the pathogen increased surviva...

Myeloperoxidase deficiency is the most common neutrophilic lysosomal enzyme deficiency. Case studies indicate that individuals with myeloperoxidase deficiency are not susceptible to serious infection in the absence of coexisting conditions such as diabetes mellitus. We present a case of myeloperoxidase deficiency manifesting as disseminated pustular candidal dermatitis in a nondiabetic male. Ce...

Prompt neutrophil arrival is critical for host defense immediately after injury [1-3]. Following wounding, a hydrogen peroxide (H(2)O(2)) burst generated in injured tissues is the earliest known leukocyte chemoattractant [4]. Generating this tissue-scale H(2)O(2) gradient uses dual oxidase [4] and neutrophils sense H(2)O(2) by a mechanism involving the LYN Src-family kinase [5], but the molecul...