Phagocyte receptors on macrophage-like cells via opsonic bridging

Phagocyte receptors on macrophage-like cells that operate via opsonic bridging represent a functional class of cell-surface proteins, primarily comprising Fc receptors (FcRs) and complement receptors (CRs) (Nimmerjahn & Ravetch, 2008, Nat Rev Immunol; Ricklin et al., 2010, Nat Immunol). These receptors are essential for the immune system's ability to identify and eliminate pathogens, apoptotic cells, and malignant cells through a process known as opsonization (Ricklin et al., 2010, Nat Immunol). In this mechanism, opsonins such as immunoglobulin G (IgG) or complement components (e.g., C3b) coat the target surface and act as molecular bridges, binding simultaneously to the target and to the corresponding receptors on the macrophage (Nimmerjahn & Ravetch, 2008, Nat Rev Immunol). This bridging event triggers complex intracellular signaling cascades, involving Src family kinases and Rho GTPases, which orchestrate the actin-dependent engulfment of the target (Nimmerjahn & Ravetch, 2008, Nat Rev Immunol). In clinical medicine, these receptors are the primary effectors for many therapeutic monoclonal antibodies, such as rituximab and trastuzumab, which induce antibody-dependent cellular phagocytosis (ADCP) (Gul & van Egmond, 2015, Cancer Cell). Polymorphisms in these receptors, particularly in the FCGR3A gene, are known to influence the clinical efficacy of such antibody-based therapies (Nimmerjahn & Ravetch, 2008, Nat Rev Immunol). Beyond cancer, these receptors play critical roles in the clearance of infectious agents and the pathogenesis of autoimmune diseases (Ricklin et al., 2010, Nat Immunol). Dysregulation of this system can lead to the destruction of healthy tissues or contribute to chronic inflammatory conditions (Shimabukuro-Vornhagen et al., 2018, J Immunother Cancer).

Other names

Fc receptorsComplement receptorsOpsonin receptorsFc gamma receptorsComplement receptor 1 (CD35)Complement receptor 3 (CD11b/CD18)Complement receptor 4 (CD11c/CD18)Phagocytic receptors

Facilitation of antibody-dependent cellular phagocytosis (ADCP) and complement-dependent phagocytosis by bridging opsonized targets to phagocytic effector cells.