Myeloperoxidase-dependent effect of amines on functions of isolated neutrophils.

Abstract

A B S T R A C T Isolated neutrophilic leukocytes were incubated with primary amines and related nitrogenous compounds. Stimulation of neutrophil oxygen (02) metabolism with phorbol myristate acetate or opsonized zymosan resulted in production of hydrogen peroxide (H202), myeloperoxidase-catalyzed oxidation of chloride (Cl-) to hypochlorous acid (HOCI), and the reaction of HOC1 with the added compounds to yield nitrogen-chlorine (N-Cl) derivatives. Formation of NCl derivatives of low lipid solubility resulted in accumulation of the derivatives in the extracellular medium. These oxidizing agents were identified and measured on the basis of their absorption spectra and their ability to oxidize 5-thio-2-nitrobenzoic acid to the disulfide form. The yield of N-Cl derivatives was in the order: taurine > Tris > spermidine > spermine > glucosamine > putrescine > guanidinoacetate. Accumulation of N-Cl derivatives was also observed in the absence of added amines, owing to the reaction of HOC1 with endogenous taurine and other amines that were released from the cells into the medium.In the presence of compounds that yield lipophilic N-Cl derivatives, little or no accumulation of oxidizing agents was observed. Instead, these compounds inhibited the accumulation of N-Cl derivatives that was obtained with taurine, and their effect was competitive with taurine. Inhibition was in the order: methylamine > ethanolamine > phenylethylamine > p-toluenesulfonamide > ammonia > guanidine. Formation of lipophilic N-Cl derivatives also resulted in inhibition of 02 uptake and glucose metabolism. Inhibition was prevented by adding catalase to eliminate H202, dapsone to inhibit myeloperoxidase, taurine to compete for reaction with HOC1, or compounds that are rapidly oxidized by HOC1 or N-Cl derivatives, to reduce these Received for publication 19 January 1983 and in revised form I April 1983. oxidizing agents. The results indicate that: (a) formation of N-Cl derivatives that do not penetrate biological membranes can protect leukocytes against the cytotoxicity of HOC1 and lipophilic N-Cl derivatives, and (b) formation of membrane-permeable N-Cl derivatives in the absence of target cells or readily oxidized substances results in oxidative attack by the NCl derivatives on leukocyte components and inhibition of leukocyte functions.

Voltage-gated proton channels maintain pH in human neutrophils during phagocytosis

“…Previous demonstration that neutrophil proteins are chlorinated extensively supports this interpretation (16). In addition, a large fraction of the O 2 ⅐ Ϫ produced by neutrophils is converted into HOCl (13)(14)(15)(16)(17). For Ϸ4 M electrons introduced cumulatively into the phagosome over a few minutes (25) at a rate of 5-20 mM s Ϫ1 (26,27), Ϸ1 M Cl Ϫ is consumed to produce HOCl (17).…”

“…Roughly half of the O 2 ⅐ Ϫ generated by NADPH oxidase during the respiratory burst of phagocytosis is converted to HOCl by myeloperoxidase (MPO) (13)(14)(15)(16)(17). We therefore inhibited MPO by including 500 M ABAH (4-aminobenzoic acid hydrazide) in the medium (18).…”

Effects of pH on killing of Staphylococcus aureus and Escherichia coli by constituents of the neutrophil phagolysosome

“…The antistaphylococcal activity of the lysosome extract-H202 combination was delayed but the effect of extract alone was actually enhanced at long incubation times. The explanation for these effects is not immediately apparent but could involve a slow interaction between NH4Cl and phagosome constituents to form toxic chloramines (Thomas et al, 1983;Weiss et al, 1983). The initial delay might then reflect preferential interaction of oxygen metabolites with NH4Cl rather than with bacteria, with long-lived chloramines contributing to late microbicidal effects.…”

Inhibition of Ammonia-Chloramine Generation and of Damage to Vascular Endothelium by Taurine and .BETA.-Alanine.

“…The spectrum of dichloramine, which has a maximum absorption of 305 nm [18], was obtained from a mixture (c) of 0.5 mlvt glycine and 1 mM HOC1. The spectrum of monochioramine at 250 nm [19] was obtained with reaction mixtures (e and f) of 20 or 50 mM glycine and 1 mlvi HOC!. Figure 2 shows ESR spectra of DMPO spin adducts observed in the reaction of 1 mlvi HOC1 with either 20 mM ammonia, taurine, or /3-alanine after incubation at 3TC for 5 min in phosphate buffer (pH 7.4).…”