Complement binding receptors
|Major Ligands||Activity||Cellular distribution|
|C3b, C4b||Blocks formation of C3 convertase, binds immune complex to cells||RBCs, neutrophils, monocytes, macrophages, eosinophils, FDCs, B cells, some T cells|
|CR2||C3d, C3dg, iC3b||Part of B-cell coreceptor, binds EBV||B cells, FDCs, some T|
|CR3, CR4||iC3b||1. Bind cell adhesion molecules on neutrophils, which facilitates extravasation.
2. Binds immune complexes, which enhances their phagocytosis.
|monocytes, macrohpages, neutrophils, NK, T-cells|
|C3a/C4a receptor||C3a, C4a||degranulation of mast cells and basophils||– Cellular distribution – mast cells, basophils, granulocytes|
|C5a receptor||C5a||induces degranulation of mast cells and basophils||Mast, basophils, granulocytes, monocytes, macrophages, platelets, endothelial cells|