Function of myeloperoxidase

The myeloperoxidase-H202 system is extremely potent in the killing of a wide range of target cells and in the inactivation of biological molecules, such as the following  

Furthermore, the myeloperoxidase systems can stimulate secretion of serotonin from platelets, histamine release from mast cells and the activation of latent collagenase and latent gelatinase of neutrophils. 

Additionally, the myeloperoxidase system even regulates the duration of the respiratory burst because neutrophils from patients with myeloperoxidase deficiency (see 8.3) generate more reactive oxidants than control cells. Also, when myeloperoxidase is inhibited with a specific antibody or a specific inhibitor such as salicylhydroxamic acid, the duration of the respiratory burst, but not the maximal rate of oxidant production, is extended. This indicates that a product of the myeloperoxidase system inhibits the NADPH oxidase and so self-regulates reactive oxidant production during inflammation. 

There is much debate as to the mechanisms by which myeloperoxidase destroys its targets. However, its abilities to generate HOC1 and chloramines and to catalyse directly the peroxidation and halogenation of the target may all be involved. Biochemical processes that may be targets for myeloperoxidase-dependent bacterial destruction include  

Overall, bacteria attacked by the myeloperoxidase system undergo a loss of selective permeability prior to death. 

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