SUMMARY, EXPLANATION AND LIMITATIONS:
This antibody recognises the secreted protein complement component 4d (C4d). The complement 1 complex cleaves complement 4 (C4) to form C4b and C4a. C4b levels are strictly regulated. Single site cleavage of the C4b’s alpha chain by Factor I forms iC4b and blocks C3 convertase, inhibiting opsonisation and activation of the classical pathway. This requires C4 binding protein or CR1 as a cofactor. iC4b is further degraded into C4d and C4c. C4d’s short half-life means that C4d is present in serum at high enough concentrations to make it a useful marker for classical complement activation. C4 has been linked to susceptibility to systemic lupus erythematosous.
Immunogen: Native, from human plasma.
Staining pattern: Cytoplasmic/Secreted.
Positive control: Tissue sample from kidney.
This antibody is designed for the specific localization of human C4d using IHC techniques in frozen tissue.