Susceptibility of Plasmodium falciparum to a peroxidase-mediated oxygen-dependent microbicidal system.

The viability of Plasmodium falciparum in culture was assessed by [3H]hypoxanthine incorporation during 24 h of incubation with lactoperoxidase, glucose-glucose oxidase, hydrogen peroxide, halides, or thiocyanate, alone or in combination. Synergistic inhibition was produced by the following combinations: lactoperoxidase plus hydrogen peroxide, lactoperoxidase plus glucose-glucose oxidase, and lactoperoxidase plus hydrogen peroxide plus halides or thiocyanate. These inhibitory effects were reversed by catalase and glutathione. The presence of plasmodial crisis forms inside the erythrocytes suggests that the oxygen-dependent microbicidal system of phagocytes has a killing effect.