Myeloperoxidase exerts microbicidal activity against Mycobacterium tuberculosis.

We investigated the antimycobacterial role of myeloperoxidase (MPO), one of the most abundant granule proteins in human neutrophils. Our data indicate that purified MPO, in the presence of hydrogen peroxide, exerts a consistent killing activity against Mycobacterium tuberculosis H37Rv and against a clinical isolate. The activity is time and dose dependent and requires the presence of chloride ions in the assay medium.