Enhanced killing of myeloperoxidase-coated bacteria in the myeloperoxidase-H2O2-Cl- system.

Bacteria preincubated with myeloperoxidase (MPO) are more readily killed upon the addition of H2O2 and Cl- than controls not subject to prior incubation. This effect was evidenced by decreased requirements of MPO and H2O2 (to approximately 33%) for equivalent bactericidal activity. MPO adsorbed onto the bacterial surface is not accessible to other competing substrates such as guaiacol and [1(-14)C] alanine. It appears that when MPO is adsorbed to the bacteria, it carries out a coupled reaction in which the activated chlorine directly attacks the bacterial cell surface.