1. Complement receptor of the Ig superfamily enhances complement-mediated phagocytosis in a subpopulation of tissue resident macrophages.
- Author
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Gorgani NN, He JQ, Katschke KJ Jr, Helmy KY, Xi H, Steffek M, Hass PE, and van Lookeren Campagne M
- Subjects
- Animals, CD18 Antigens immunology, Calcium immunology, Gene Expression Regulation immunology, Ligands, Magnesium immunology, Mice, Mice, Inbred AKR, Mice, Knockout, Receptors, Complement agonists, Complement C3 immunology, Macrophages immunology, Phagocytosis immunology, Receptors, Complement immunology
- Abstract
An important function of the complement cascade is to coat self and foreign particles with C3-proteins that serve as ligands for phagocytic receptors. Although tissue resident macrophages play an important role in complement-mediated clearance, the receptors coordinating this process have not been well characterized. In the present study, we identified a subpopulation of resident peritoneal macrophages characterized by high expression of complement receptor of the Ig superfamily (CRIg), a recently discovered complement C3 receptor. Macrophages expressing CRIg showed significantly increased binding and subsequent internalization of complement-opsonized particles compared with CRIg negative macrophages. CRIg internalized monovalent ligands and was able to bind complement-opsonized targets in the absence of Ca(2+) and Mg(2+), which differs from the beta(2)-integrin CR3 that requires divalent cations and polyvalent ligands for activation of the receptor. Although CRIg dominated in immediate binding of complement-coated particles, CRIg and CR3 contributed independently to subsequent particle phagocytosis. CRIg thus identifies a subset of tissue resident macrophages capable of increased phagocytosis of complement C3-coated particles, a function critical for immune clearance.
- Published
- 2008
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