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Updated: Jul 28, 2026
Fast and Specific Assessment of the Halogenating Peroxidase Activity in Leukocyte-enriched Blood Samples
Published on: July 28, 2016
Plasma concentration of myeloperoxidase enzyme in pre- and post-climacterial people: related superoxide anion
12nd Department of Medicine, Semmelweis University, Szentkirályi Utca 46, 1088, Budapest, Hungary. bg@mail.digitel2002.hu
Abstract:
Neutrophil granulocytes are involved in the pathogenesis of atherosclerosis also through their free radical generation. The aim of the study was to test how extracellular levels of myeloperoxidase (MPO; a granulocyte enzyme playing role in free radical production) change by age and what effect this change has on the production of the free radical superoxide anion by neutrophils. We also wanted to examine whether the antioxidant effect of different steroid hormones is realized through the MPO. Plasma myeloperoxidase concentrations of healthy blood donors were quantified by ELISA. Superoxide anion production was measured by photometry. Myeloperoxidase concentration was significantly lower in plasmas obtained from older women and men than in those from younger subjects. Adding the MPO inhibitors 4-aminobenzoic acid hydrazide (ABAH) and indomethacin to the granulocytes, the generation of superoxide anion increased and the decreasing effect of the steroids on superoxide production was inhibited. Incubating the neutrophils with the product of the reaction catalyzed by MPO itself (hypochlorite anion), we found significant decrease in superoxide generation. According to our results MPO seems to diminish the production of superoxide anion and so probably has an antioxidant ability. Therefore, its lower plasma levels may contribute to the increasing incidence of atherosclerosis and other free radical mediated disorders in old people. Thus, after further studies MPO might become one of the indicators of cardiovascular risk and the scavenger capacity in general.
Insights
Plasma myeloperoxidase (MPO) levels decrease with age, potentially increasing oxidative stress and cardiovascular risk. Lower MPO may impair the body's antioxidant capacity, contributing to age-related diseases.
Area of Science:
- Biochemistry
- Immunology
- Cardiovascular Science
Background:
- Neutrophil granulocytes contribute to atherosclerosis via free radical generation.
- Myeloperoxidase (MPO) is a key granulocyte enzyme in free radical production.
Purpose of the Study:
- To investigate age-related changes in extracellular MPO levels.
- To determine the effect of MPO levels on neutrophil superoxide anion production.
- To examine if steroid hormones' antioxidant effects are mediated by MPO.
Main Methods:
- Quantified plasma MPO concentrations using ELISA in healthy blood donors.
- Measured superoxide anion production via photometry.
- Utilized MPO inhibitors (4-aminobenzoic acid hydrazide, indomethacin) and MPO reaction products (hypochlorite anion).
Main Results:
- Significantly lower MPO concentrations were observed in older adults compared to younger subjects.
- Inhibition of MPO increased superoxide anion generation and blocked steroid-induced reduction of superoxide production.
- Incubation with hypochlorite anion decreased superoxide generation, suggesting MPO's antioxidant role.
Conclusions:
- MPO appears to reduce superoxide anion production, indicating an antioxidant function.
- Lower plasma MPO levels in older individuals may increase susceptibility to atherosclerosis and other free radical-mediated disorders.
- MPO warrants further study as a potential biomarker for cardiovascular risk and general scavenger capacity.
