Phagocyte activation

Phagocyte activation describes the state in which immune cells known as phagocytes (macrophages, neutrophils, dendritic cells, monocytes) become functionally primed or stimulated, typically in response to infectious or inflammatory signals. This priming occurs via the recognition of pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) through pattern-recognition receptors (PRRs), Fcγ receptors, complement receptors, or other opsonic and non-opsonic receptors. Upon activation, phagocytes increase surface expression of adhesion molecules and phagocytic receptors, enhance their microbicidal and metabolic activity, produce inflammatory cytokines, and migrate to sites of infection or injury, where they ingest and degrade pathogens and cell debris. Overactivation can lead to collateral tissue damage, while insufficient activation compromises host defense.

Other names

Phagocyte primingactivation of phagocytosisstimulated phagocytesinflammatory activation of phagocytes

Inhibition or upregulation of surface receptors (FcγR, complement receptors); modulation of intracellular signaling pathways (e.g., Rho GTPase, PI3K, PKC); modulation of cytokine production; and suppression/activation of actin cytoskeletal rearrangement.