Table 1.
(Top) Complement nomenclature as per International Complement Society (ICS) Complement Nomenclature Committee, and ICS and European Complement Network (ECN) boards recommendation from 2014 [reproduced with permission (5)].
| Recommended 2014 | Recommended 2014 | ||
|---|---|---|---|
| Name | Comments | Name | Comments |
| Pathways | Proteins (cont.) | ||
| CP | Classical pathway | MBL | Mannose-binding lectin |
| AP | Alternative pathway | Ficolin-1 | Ficolin M |
| LP | Lectin pathway | Ficolin-2 | Ficolin L |
| TP | Terminal pathway (C5, C6, C7, C8, and C9) | Ficolin-3 | Ficolin H |
| Proteins | MASP-1 | MBL-associated serine protease 1 | |
| C1 | Complex of C1q, 2C1r, 2C1s | MASP-2 | MBL-associated serine protease 2 |
| C1q | MASP-3 | MBL-associated serine protease 3 | |
| C1r | FHL-1 | Factor H-like protein 1 | |
| C1s | FHR-1 | Factor H-related protein 1 | |
| C1-INH | C1 Esterase inhibitor | FHR-2 | Factor H-related protein 2 |
| C2 | FHR-3 | Factor H-related protein 3 | |
| C3 | FHR-4 | Factor H-related protein 4 | |
| C3(H2O) | Thioester-hydrolyzed form of C3 | FHR-5 | Factor H-related protein 5 |
| C3a | Anaphylatoxin from C3 | CD59 | Protectin, Homologous restriction factor |
| C3b | Protein complexes | ||
| iC3b | Inactivated C3b | C5b6 | Terminal pathway complex of C5b + C6 |
| C3dg | C5b-7 | Terminal pathway complex of C5b6 + C7 | |
| C3d | C5b-8 | Terminal pathway complex of C5b-7 + C8 | |
| C4 | C5b-9 | Terminal pathway complete complex | |
| C4a | sC5b-9 | Soluble C5b-9 with Vn bound | |
| C4a-desArg | C4a without C-terminal arginine | C3bBb | AP C3 convertase |
| C4b | C3bBbP | AP C3 convertase with properdin | |
| C4d | C3bBbC3b | AP C3/C5 convertase | |
| C4BP | C4b binding protein | C4BP-Protein S | C4BP bound to protein S |
| C5 | Receptors | ||
| C5a | Anaphylatoxin from C5 | CR1 | CD35, C3b/C4b receptor |
| C5a-desArg | C5a without C-terminal arginine | CR2 | CD21, C3d receptor |
| C5b | CR3 | CD11b/CD18 complex | |
| C6 | CR4 | CD11c/CD18 complex | |
| C7 | C3aR | Requesting CD number | |
| C8 | C5aR1 | C5aR, CD88 | |
| C9 | C5aR2 | C5L2, requesting CD number | |
| Vn | Vitronectin, S protein, S40 | CRIg | Complement receptor of the Ig family |
| FB | Factor B | C1qR | |
| FD | Factor D | gC1qR | Recognizes globular domains |
| FH | Factor H | cC1qR | Recognizes collagen domain, calreticulin |
| FI | Factor I | LHR | Long homologous repeat (CR1) |
| UPDATED COMPLEMENT NOMENCLATURE 2019 | |||
| Proteins | Lectin pathway | ||
| C2a | Small C2 cleavage fragment | CL-10 | Collectin-10 |
| C2b | Large C2 cleavage fragment – enzyme | CL-11 | Collectin-11 |
| CLU | Clusterin (ApoJ, Sp40,40) | MAP-1 | Previously Map44 |
| Properdin | MAP-2 | Previously Map19, sMAP | |
| Protein complexes | |||
| C1 | C1qr2s2 | ||
| Activated C1 | Activated complex (containing activated/cleaved C1s) | ||
One modification was made to remove 2014 proposed nomenclature for clusterin. (Bottom) (gray): updated complement nomenclature.