Diversity in Motile Responses of Human Neutrophil Granulocytes: Functional Meaning and Cytoskeletal Basis

Abstract

Neutrophil granulocytes are multifunctional cells, capable of locomotion, Chemotaxis, adhesion, pinocytosis, phagocytosis, intracellular killing or degradation and exocytosis. Several of the functions require generation of force and may thus be associated with different forms of motility. In the circulating blood of healthy individuals neutrophils are in a relatively quiescent state, i.e. they are spherical and nonmotile. Activation and regulation of neutrophil functions can, to some extent, occur in a selective manner. Most agonists activate only some neutrophil functions but not others. Or they stimulate at least some functions to a much greater extent than others. Chemotaxis for example is an important neutrophil function, but only few agonists are actually chemotactic, while many others are not. Furthermore an agonist, e.g. a chemotactic factor, may elicit pinocytosis or Chemotaxis at lower concentrations than exocytosis (Davis et al., 1986). Such qualitative, quantitative and temporal differences may help to understand the relationship, if any, between these functions. Thus, the F-actin peak preceeds the time maximum for pinocytosis (Davis et al., 1986), and the maximal pinocytotic response occurs at an earlier time point than full development of polarity (Fig. 1) and locomotion.