Human C3b/Complement Fragment 3b ELISA Kit

A colorimetric sandwich ELISA from Assay Genie designed for the quantitative detection of C3b/Complement Fragment 3b in human samples. The kit is reactive with human specimens and accepts serum, plasma, cell culture supernatant, cell or tissue lysate, and other liquid samples. Sensitivity is reported as 0.188 ng/mL with a working range of 0.313-20 ng/mL. The assay uses a double-antibody sandwich format with a biotin-labelled detection antibody and HRP-Streptavidin (SABC) for signal generation, developed with TMB substrate and read at 450 nm.

Linearity in serum (n=5) was 83-101% at 1:2, 85-94% at 1:4 and 85-95% at 1:8. EDTA plasma (n=5) showed 83-98%, 82-97% and 92-101% at the same dilutions, and heparin plasma (n=5) gave 82-98%, 86-100% and 84-95%. Spike-and-recovery across serum, EDTA plasma and heparin plasma averaged 99%, 94% and 95% respectively. Unopened kit components are stored at 2-8°C for 12 months. The protocol follows six steps beginning with reagent equilibration and a 90-minute primary incubation at 37°C, followed by a 60-minute detection-antibody step and a 30-minute SABC incubation, then 10-20 minutes of TMB colour development in the dark and absorbance measurement after stop solution is added.

C3b is a key component of the complement system involved in immune response and inflammation, and its dysregulation has been associated with autoimmune diseases, infections and inflammatory conditions.