Phagocytosis and Oxidative Burst: Reference Values for Flow Cytometric Assays Independent of Age

The main function of neutrophils is to provide a front line of defense against invasive bacteria. Disturbances in the functioning of neutrophils lead to repeated and life-threatening infections caused by bacteria and fungi (1)(2). Pathological neutrophil functions are detected as permanent inborn metabolic defects of NADPH oxidase with oxidative burst [chronic granulomatous disease (CGD) (2)(3)], glutathione peroxidase (4), and adhesion molecules (2)(5). Moreover, transient disturbances of phagocytosis may be detected in systemic infections (5)(6)(7)(8)(9), acute pancreatitis (10), tuberculosis (11), and Wegner granulomatosis (12), as well as under special conditions such as in newborns (6)(13)(14), very old persons (15), or in persons undergoing therapies with cytokines, prednisolone, or anesthetics (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(14)(16). The following clinical and laboratory findings indicate that assessment of granulocyte function is needed: increased susceptibility to bacterial infections, therapy-resistant infections, recurrent infections with nonpathogenic microorganisms, lymphadenitis, abscesses of liver or lung, osteomyelitis, recurrent stomatitis, or gingivitis. Granulocytopenia and defects of B cells or complement compartment must be excluded (17). Phagocytosis, adhesion molecules CD18 and CD11b for leukocyte adhesion defect I or CD15s for leukocyte adhesion defect II, and production of oxygen radicals upon stimulation for CGD can be tested by flow cytometric determinations. Disturbances such as Chédiak-Higashi syndrome, hyper IgE syndrome, or glycogenesis type Ib need other techniques.