Fc gamma receptor III induces actin polymerization in human neutrophils and primes phagocytosis mediated by Fc gamma receptor II.

Abstract

Human polymorphonuclear leukocytes (PMN) express two classes of Fc gamma R: Fc gamma RII the 42-kDa receptor with a traditional membrane spanning domain and cytoplasmic tail and Fc gamma RIIIPMN the 50- to 80-kDa receptor with a glycosyl-phatidylinositol membrane anchor expressed on PMN. To explore the capacity of Fc gamma RIIIPMN to generate intracellular signals, we have analyzed the ability of Fab and F(ab')2 anti-Fc gamma R mAb to induce actin filament assembly, a prerequisite for motile behaviors. Multivalent ligation of Fc gamma RIIIPMN, independent of Fc gamma RII, results in an increase in F-actin content that is [Ca2+]i dependent. Multivalent ligation of Fc gamma RII also initiates actin polymerization but uses a [Ca2+]i-independent initial pathway. In addition to providing a mechanism for Fc gamma RIIIPMN triggered effector functions, the increase in F-actin and [Ca2+]i generated by Fc gamma RIIIPMN ligation also serves as a "priming" signal to modify PMN responses to other stimuli. Experiments using erythrocytes specifically coated with anti-Fc gamma RII Fab demonstrate that cross-linking of Fc gamma RIIIPMN with anti-Fc gamma RIII F(ab')2 enhances phagocytosis mediated by Fc gamma RII. Thus, Fc gamma RIIIPMN, a glycosyl-phosphatidylinositol anchored protein, may contribute directly to an intracellular program of actin assembly that may trigger and prime neutrophil effector functions.

CD66-mediated phagocytosis of Opa52 Neisseria gonorrhoeae requires a Src-like tyrosine kinase- and Rac1-dependent signalling pathway

“…The uptake of particles by phagocytes involves opsonin‐independent as well as opsonin‐dependent pathways. One of the best characterized opsonin‐dependent pathways is the Fcγ‐receptor‐mediated internalisation of antibody‐coated particles or bacteria (Sheterline et al ., 1984; Salmon et al ., 1991; Zheleznyak and Brown, 1992; Davis et al ., 1995). In this case, phagocytosis of bacteria is mediated by specific antibodies linking the bacterial surface to phagocyte Fcγ‐receptors.…”

Phosphatidylserine clustering by membrane receptors triggers LC3-associated phagocytosis

“…Next, we expanded our investigations to include receptors other than TLRs whose cargoes are also known to induce LAP, such as CD16, a component of the Fc receptor (FcR) that binds IgG 17 , and Tim4 that binds dead and dying cells 6 . IgG-coated beads induced enrichment of PS in the phagosome, as assessed by Venus-Lact-C2 recruitment (Fig.…”