The respiratory burst of phagocytic cells is associated with a rise in vacuolar pH

Abstract

Neutrophil leukocytes are the body's major defence against bacteria, which they phagocytose and kill. It has been found that phagocytosis and killing are accompanied by a dramatic rise in non-mitochondrial respiration^1,2; and that the efficiency of killing is impaired in the absence of oxygen^3,4. It is also impaired in neutrophils from patients with chronic granulomatous disease (CGD), where the respiratory burst is absent⁵. This has been difficult to reconcile with their normal content of granule proteins that kill bacteria in vitro⁶. Indeed, CGD cells are essentially normal both morphologically and constitutionally^7,8 except that they lack a functional very low potential cytochrome b (b₋₂₄₅)⁹ which is a component of the oxidase system responsible for the respiratory burst of normal cells^10,11. Activation of the oxidase is associated with the generation of various reduced oxygen species^12–16 which have been widely thought to be responsible for the killing of phagocytosed microorganisms either directly¹⁷, or by acting as substrates for myeloperoxidase-mediated halogenation¹⁸. We report here, however, that a major consequence of the defective function of this oxidase in neutrophils and monocytes from CGD patients is an absence of the normal initial rise, and an unusually rapid and extensive fall in pH which is itself associated with the impairment of the killing and digestion of intracellular staphylococci.