Mobilization and adaptation of human neutrophil chemoattractant fMet-Leu-Phe receptors.

Neutrophil responsiveness to N-formylmethionylleucylphenylalanine (fMet-Leu-Phe) appears to involve either receptor recycling and/or a storage pool of receptors that provide a mechanism for replenishment of receptors at the cell surface. Asymmetric distribution of the fMet-Leu-Phe receptor has been shown by others, with increased receptor density reported at the front of the cell. This receptor asymmetry may result from receptor capping in the front, receptor internalization or shedding in the rear, or addition of new receptors at the front of the cell. In addition to receptor asymmetry, affinity adaptation of the receptor through heterogeneity and/or negative cooperative interaction of the receptors is probably important. It has been suggested that a high-affinity state of the receptor is associated with transduction of chemotaxis and a low-affinity state with transduction of superoxide production and degranulation. Thus, the fMet-Leu-Phe receptor is an important model to study how neutrophils recognize and integrate signals for their complex functions.