Complement binding receptors
Complement binding receptors
| Major Ligands | Activity | Cellular distribution | |
| CR1
|
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 |