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Chlorination of endogenous amines by isolated neutrophils. Ammonia-dependent bactericidal, cytotoxic, and cytolytic activities of the chloramines.

Year: 1984
Type: article
Abstract: Isolated human neutrophilic leukocytes were stimulated to produce hydrogen peroxide (H2O2) and to secrete cytoplasmic granule components including myeloperoxidase into the medium. Myeloperoxidase catalyzed the oxidation of chloride (Cl-) by H2O2 to yield hypochlorous acid (HOCl), which reacted with endogenous nitrogen compounds to yield derivatives containing nitrogen-chlorine (N-Cl) bonds. Compounds available for reaction with HOCl were ammonia (NH+4), taurine, alpha-amino acids, and granule proteins and peptides that were released into the medium. A portion of the N-Cl derivatives formed under these conditions accumulated in the extracellular medium. These long lived oxidizing agents were characterized as hydrophilic, low molecular weight, mono-N-chloramine (RNHCl) derivatives based on their absorption spectrum, ability to oxidize 5-thio-2-nitrobenzoic acid and to chlorinate ammonia (NH+4), and behavior upon ultrafiltration, gel chromatography, and extraction with organic solvents. The RNHCl derivatives were of low toxicity, but reacted with NH+4 to yield the lipophilic oxidizing agent monochloramine (NH2Cl). Therefore, the addition of NH+4 conferred bactericidal, cytotoxic, and cytolytic activities on the RNHCl derivatives. The results indicate that taurine and other neutrophil amines protect neutrophils and other cells against oxidative attack by acting as a trap for HOCl and by competing with endogenous NH+4 for reaction with HOCl. However, the RNHCl derivatives act as a reserve of oxidizing equivalents that is converted to a toxic form when an increase in NH+4 concentration favors formation of NH2Cl.
DOI: 10.1016/s0021-9258(18)90979-8
Language: English
Subfield: Immunology
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1586360287
FWCI: 4.308
Cites: 66
Cited by: 396
Related to: 10