Asymmetric Fc receptor distribution on human PMN oriented in a chemotactic gradient.

Phagocytosis of antibody-coated particles and immune complexes by polymorphonuclear leukocytes (PMN) and macrophages is initiated by binding to Fc receptors. While it appears that subsequent ingestion requires receptor-Fc interactions to occur along the entire periphery of the particle, the distribution of Fc receptors over the leukocyte surface is unknown. We show here that during chemotaxis the Fc receptors of human neutrophils are localized to the cell's leading edge. This restricted receptor topography coincides with cell orientation and does not require net forward movement of PMN. Thus Fc receptors are located in precisely that region of the cell most likely to first encounter opsonized particles.