Name: C3d Antibody
Description and applications: This antibody recognises the C3d fragment of the complement. Component C3 can be activated through both classical and alternative complement pathways. Among the different complement proteins, C3 and C4 opsonins have a protective thioester radical. This molecule enables C3 (and C4) complement fragments to form covalent bonds when activated by the target molecule, generating C3b. The proteolytic cleavage of C3b generates the C3d fragment, which remains covalently attached to the target structure, while the C3c fragment is released. The C3d fragment is stable and it can be identified in paraffin-embedded biopsies. Under normal conditions, renal glomerular capillaries are stained. In transplants, the identification of diffuse deposits of C3d and C4d in renal peritubular capillaries or cardiac capillaries supports the diagnosis of acute humoral rejection of the graft. Deposits of C3d have been identified in grafts with chronic rejection but its significance has yet to be clarified. Deposition of C3d on paraffin-embedded biopsies from skin inflammatory pathologies has been demonstrated by different authors. Magro and Dyrsen identified prominent granular C3d deposits along the dermoepidermal junction for all discoid lupus erythematosus (20/20) and systemic LE (5/5) cases. In systemic LE, vascular C3d or C4d deposits were shown. All cases of urticarial (5), leukocytoclastic (6), and lymphocytic (1) vasculitis exhibited prominent mural C3d and C4d deposits in vessels, whereas Henoch-Schönlein purpura (10/10) showed only C3d deposits. Pfaltz et al found deposits of C3d at the epidermal basement membrane in 97% (31/32) of bullous pemphigoid cases.
Composition: anti-human C3d Complement Component rabbit polyclonal antibody purified from serum and prepared in 10mM PBS, pH 7.4, with 0.2% BSA and 0.09% sodium azide
IHC positive control: Kidney tissue section with acute humoral rejection.