Measurement of opsonic phagocytosis by human polymorphonuclear neutrophils

Abstract

Publisher Summary This chapter discusses the measurement of opsonic phagocytosis by human polymorphonuclear neutrophil (PMN). Phagocytosis is recognized as a primary and critical cell function in host defense. In higher vertebrates, such as humans, this function is performed largely by “professional” phagocytes like the PMN. Termed opsonins (from the Greek opsonion , “a relish, seasoning, or sauce”), these humoral factors bind to the surface of foreign material and, engage receptors on the phagocytic cell surface that initiate the endocytic (phagocytic) process. Measurements of phagocytosis of microbial parasites by phagocytic cells such as PMNs have employed a wide variety of techniques that can be broadly divided into two main categories: (1) direct measures of phagocyte-target interactions and (2) indirect measures that quantitate metabolic events or biochemical markers associated with ingestion and cellular activation, such as lysosomal enzyme release, superoxide anion (O 2 -) production, and chemiluminescence. The three direct techniques for the measurement of phagocytosis are presented. The first is a novel flow cytometric assay that uses unfractionated whole blood. The second, a fluorescence microscopic method compatible with a wide variety of microorganisms, employs cytocentrifugation and cell fixation. The third is an adaptation of the oil red O method originally described by Stossel in 1973 to the user- (and technology-) friendly 96-well microtiter plate format.