Quercetin, a regulator of polymorphonuclear leukocyte (PMNL) functions.

The binding of certain small peptides, proteins or amphipathic compounds to the surface of polymorphonuclear leukocytes (PMNL) may promote a specific activation of cell functions, such as motility, endocytosis, oxidative metabolism and secretion (9,10,12–18,20,23,25,26,31,33,35,37,39,41). The molecular mechanisms, by which this surface interaction is translated into “signals” stimulating various biochemical pathways in the PMNL, have been the subject of intense investigation for several years. The current theory is that the coordinated response of PMNL to environmental changes is triggered by a cascade of events, presumably with the utilization of some key steps for the stimulation of various cell activities. For example, an elevation of cytosol free calcium concentrations appears to be required for the enhancement of PMNL directional locomotion (38), oxidative metabolism (24,28,30) and extracellular secretion of granule enzymes (34,40).