Exogenous myeloperoxidase enhances bacterial phagocytosis and intracellular killing by macrophages

Abstract

It is well documented that myeloperoxidase (MyPo) contributes to the bactericidal activities of neutrophils and monocytes. Since mature macrophages (M) are devoid of this enzyme, its participation in M-mediated phagocytosis and bacterial killing has not been completely defined. The present study demonstrates that exogenously added MyPo, at physiological levels, enhances both phagocytosis and killing of Escherichia coli. Murine peritoneal M were exposed to various concentrations of MyPo for different time intervals. Viable opsonized E. coli was added either prior to or after addition of MyPo. Thioglycolate-induced but not resident M exhibited an increase in the number of phagocytizing cells. Both resident and thioglycolate-induced M demonstrated increased bactericidal activity. Physiological levels of soluble MyPo also induced a significant increase in chemiluminescence. Since luminol-dependent chemiluminescence measures reactive oxygen intermediate production, studies were done to determine whether superoxide anion or H 2 O 2 was involved in MyPo-induced M killing. Both superoxide dismutase and catalase ablated MyPo-induced bactericidal activity. The above data suggest that soluble MyPo, released from neutrophils at a site of infection or inflammation, can enhance both phagocytosis and killing of microorganisms.

Differences in platelet growth factor release and leucocyte kinetics during autologous platelet gel formation

“…There, MPO catalyses the oxidation of chloride to generate hypochlorous acid and other reactive oxygen derivates. These substances act as potent bactericidal oxidants and are toxic to microorganisms and fungi (Lincoln et al, 1995). Our study showed that the amount of neutrophils and monocytes are significantly elevated in the BC-PRP, whereas the ratio of these cells is altered when compared with the baseline whole blood values.…”

“…PG has been cited in publications as a technique for the local delivery of GF. However, little attention has been given to the role of the WBC, despite the fact that PG is a buffy coat product, including both neutrophils and monocytes containing high levels of myeloperoxidase (MPO), which might contribute to bacterial killing (Lincoln et al, 1995). Theoretically, PG might be an ideal autologously prepared biological blood product, rich in GFs with enhanced antimicrobacterial capabilities.…”

Antimicrobial activity of a porcine myeloperoxidase against plant pathogenic bacteria and fungi

“…The antimicrobial activity of myeloperoxidase has been intensively studied in mammalian systems (Klebanoff 1968;Wright et al 1983;Chase and Klebanoff 1992;Chochola et al 1994;Cooray and Björck 1995;Lincoln et al 1995;Hampton et al 1996;Lefkowitz et al 1996). However, few experiments have been conducted to evaluate this enzyme closely for its © 1999 The Society for Applied Microbiology, Journal of Applied Microbiology 86, 211-220 usefulness in controlling plant pathogens (Jacks et al 1991).…”

Peroxidase activity as a measure of neutrophil populations in inflammatory peritoneal exudates of rainbow trout, Oncorhynchus mykiss (Walbaum)

“…Additionally, it has been shown that the released, extracellular peroxidase does not persist, at least with enzymatic activity, for long periods of time. This is because: (1) free peroxidase is rapidly inactivated by the oxygen radicals generated by reactions catalysed by the peroxidase itself (Bradley et al 1982;Edwards, Nurcombe & Hart 1987;King et al 1997); and (2) the peroxidase molecule is taken up by leucocytes, especially macrophages, present in the inflamed exudates (Shellito, Sniezek & Warnock 1987;Leung & Goren 1989;Lincoln, Lefkowitz, Cain, Castro, Mills, Lefkowitz, Moguilevsky & Bollen 1995). It has been shown that the macrophage mannose receptor is involved in the uptake (Shepherd & Hoidal 1990;Lefkowitz, Lincoln, Lefkowitz, Bollen & Moguilevsky 1997).…”