Purified anti-Cytochrome b-245 heavy chain

The integral membrane protein flavocytochrome b (Cyt b), a heterodimer formed by a 91-kD glycoprotein (heavy chain) and a 22-kD polypeptide (light chain), is the catalytic core of the phagocyte NADPH oxidase and generates superoxide which plays a critical role in host defense. NADPH oxidase is a central well characterized component of the innate immune response against fungal and bacterial infections. Recent research also offers new insight into a novel role for this oxidase in the coordination of the adaptive immune response. CYBB deficiency is one of five described biochemical defects associated with chronic granulomatous disease (CGD). In this disorder, there is decreased activity of phagocyte NADPH oxidase; neutrophils are able to phagocytize bacteria but cannot kill them in the phagocytic vacuoles. The cause of the killing defect is an inability to increase the cell's respiration and consequent failure to deliver activated oxygen into the phagocytic vacuole.