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- Title
Dynamic macrophage "probing" is required for the efficient capture of phagocytic targets.
- Authors
Flannagan, Ronald S.; Harrison, Rene E.; Yip, Christopher M.; Jaqaman, Khuloud; Grinstein, Sergio
- Abstract
Binding of ligands by immunoreceptors is thought to be a passive, stochastic process. Contrary to this notion, we found that binding of IgG-opsonized particles by Fcγ receptors was inhibited in macrophages, dendritic and microglial cells by agents that interfere with actin assembly or disassembly. Changes in the lateral mobility of the receptors--assessed by single-particle tracking--or in the microelasticity of the membrane--determined by atomic-force microscopy--could not account for the effects of actin disruption on particle binding. Instead, we found that the macrophages contact their targets by actively extending actin-rich structures. Formation of these protrusions is driven by Rac and requires phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. Capture of C3bi-opsonized as well as unopsonized targets by macrophages was also dependent on actin. Thus, phagocytes continuously probe their environment for foreign particles in a manner akin to the constitutive sampling of the fluid milieu by dendritic cells. Active probing by phagocytes is most important when confronted by scarcely opsonized and/or highly mobile targets.
- Subjects
MACROPHAGES; PHAGOCYTOSIS; LIGANDS (Biochemistry); NEUROGLIA; ACTIN
- Publication
Journal of Cell Biology, 2010, Vol 191, Issue 6, p1205
- ISSN
0021-9525
- Publication type
Article
- DOI
10.1083/jcb.201007056