Human C4d/Complement Fragment 4d ELISA Kit

A colorimetric sandwich ELISA designed for the quantitative measurement of human Complement Fragment 4d (C4d) in serum, plasma, cell culture supernatant, cell or tissue lysate, and other liquid samples. Produced by Assay Genie, the kit uses a double-antibody sandwich detection format and is intended for research applications studying the complement system, immune response, and inflammation. Elevated C4d levels have been associated with autoimmune diseases, organ transplant rejection, and inflammatory conditions, supporting the analyte's value as a research biomarker.

The assay has a sensitivity of 0.375 ng/mL and a measuring range of 0.625–40 ng/mL, with absorbance read at 450 nm after TMB substrate development. Storage is at 2–8°C for 12 months. Linearity values (n=5) are reported as 86–104% for serum across 1:2, 1:4 and 1:8 dilutions, 85–95% / 86–98% / 84–100% for EDTA plasma at the same dilutions, and 81–97% / 82–100% / 86–91% for heparin plasma. Spike-and-recovery performance is 88–105% (mean 96%) for serum, 90–105% (mean 97%) for EDTA plasma, and 86–98% (mean 90%) for heparin plasma.

The procedure runs through reagent and plate preparation, primary incubation at 37°C, biotinylated detection antibody binding, HRP-streptavidin incubation, TMB colour development in the dark, and a stop reaction with immediate absorbance measurement at 450 nm.