The respiratory burst is a rapid increase in oxygen consumption by phagocytes (neutrophils, eosinophils, and mononuclear phagocytes) in response to stimuli. This process involves the production of superoxide (O₂⁻) and hydrogen peroxide (H₂O₂), along with increased glucose metabolism via the hexose monophosphate shunt. The primary purpose of this burst is not energy production but the generation of microbicidal agents. The burst is initiated by the activation of a dormant enzyme, pyridine nucleotide oxidase, which catalyzes the one-electron reduction of oxygen to O₂⁻ using NADPH. This enzyme is located in the plasma membrane and is crucial for the respiratory burst. The O₂⁻ produced is rapidly dismutated to form H₂O₂. These compounds are not directly microbicidal but serve as precursors for more potent oxidants. The main microbicidal oxidants are oxidized halogens, such as hypochlorite, and oxidizing radicals, including the hydroxyl radical. Hypochlorite is produced by the myeloperoxidase-catalyzed oxidation of Cl⁻ by H₂O₂. The hydroxyl radical is generated through a metal-catalyzed reaction between O₂⁻ and H₂O₂. The respiratory burst was first discovered in 1933 but was not widely recognized until the 1960s. It is now a subject of extensive research, with many scientists investigating its mechanisms and implications. The enzyme responsible for the respiratory burst is the membrane-associated pyridine nucleotide oxidase. Recent studies have focused on the role of cytochrome b in the electron transport chain and the activation of the oxidase by various stimuli, including inflammatory mediators. The activation of the oxidase involves complex biochemical pathways and is influenced by factors such as membrane potential changes and calcium levels. Additionally, activation of mononuclear phagocytes by endotoxin or γ-interferon leads to increased respiratory burst activity. The respiratory burst also contributes to genetic mutations in bacteria and mammalian cells, suggesting a potential carcinogenic role for phagocytes. The study of the respiratory burst continues to reveal new insights into phagocyte function and microbial defense mechanisms.The respiratory burst is a rapid increase in oxygen consumption by phagocytes (neutrophils, eosinophils, and mononuclear phagocytes) in response to stimuli. This process involves the production of superoxide (O₂⁻) and hydrogen peroxide (H₂O₂), along with increased glucose metabolism via the hexose monophosphate shunt. The primary purpose of this burst is not energy production but the generation of microbicidal agents. The burst is initiated by the activation of a dormant enzyme, pyridine nucleotide oxidase, which catalyzes the one-electron reduction of oxygen to O₂⁻ using NADPH. This enzyme is located in the plasma membrane and is crucial for the respiratory burst. The O₂⁻ produced is rapidly dismutated to form H₂O₂. These compounds are not directly microbicidal but serve as precursors for more potent oxidants. The main microbicidal oxidants are oxidized halogens, such as hypochlorite, and oxidizing radicals, including the hydroxyl radical. Hypochlorite is produced by the myeloperoxidase-catalyzed oxidation of Cl⁻ by H₂O₂. The hydroxyl radical is generated through a metal-catalyzed reaction between O₂⁻ and H₂O₂. The respiratory burst was first discovered in 1933 but was not widely recognized until the 1960s. It is now a subject of extensive research, with many scientists investigating its mechanisms and implications. The enzyme responsible for the respiratory burst is the membrane-associated pyridine nucleotide oxidase. Recent studies have focused on the role of cytochrome b in the electron transport chain and the activation of the oxidase by various stimuli, including inflammatory mediators. The activation of the oxidase involves complex biochemical pathways and is influenced by factors such as membrane potential changes and calcium levels. Additionally, activation of mononuclear phagocytes by endotoxin or γ-interferon leads to increased respiratory burst activity. The respiratory burst also contributes to genetic mutations in bacteria and mammalian cells, suggesting a potential carcinogenic role for phagocytes. The study of the respiratory burst continues to reveal new insights into phagocyte function and microbial defense mechanisms.