Complement component C4d
| Complement component C4d | ||
|---|---|---|
| Mass / length primary structure | 380 amino acids | |
| Precursor | C4b (690 aa) | |
| Identifier | ||
| Gene name (s) | C4A , C4B | |
| External IDs | ||
The complement component C4d is a protein of the immune system that is produced via the classic antibody- mediated route. The laboratory detection of C4d in the tissue of a transplanted organ is currently the best marker for an antibody-mediated rejection reaction . Mutations in C4A - gene are for hereditary autoimmune diseases responsible.
C4d is a cleavage product of the complement protein C4. It contains a hidden sulfhydryl group which, when activated by antibodies and C1, forms a covalent thioester bond with neighboring proteins . After activation, C4d remains in the tissue for several days. The functional importance of the C4d bond is unknown. In the rejection of transplanted organs C4d is highly associated with circulating antibodies to HLA class I and class II antigens .
literature
- HE Feucht et al .: Capillary deposition of C4d complement fragment and early renal graft loss. In: Kidney International . 43, 1993, 1333-1338; doi : 10.1038 / ki.1993.187
- RB Colvin: Antibody-Mediated Renal Allograft Rejection: Diagnosis and Pathogenesis In: J Am Soc Nephrol . 2007, 18, 1046-1056