The importance of oxidative killing effector pathway is underlined by the findings that chronic granulomatous disease and myeloperoxidase deficiency, where ROS production is defective in neutrophils, impair C. albicans killing in both patients and mice (Aratani et al, 1999, 2002, Lehrer & Cline, 1969). Here, MPO is linked to chronic granulomatous disease.