The Human Complement 3 (C3) ELISA Kit is used to quantitatively measure the concentrations of C3 in human serum, plasma, cell culture supernates, urine, or saliva. This assay employs the quantitative sandwich enzyme immunoassay technique, in which C3 in the samples or standards are sandwiched between pre-coated C3 antibody and HRP-conjugated antibody specific for C3. Following a wash to remove any unbound reagent, the TMB substrate solution is added to the wells and color develops in proportion to the amount of C3 bound in the initial step. The color development is stopped and the intensity of the color is measured at 450 nm via a microplate reader. This kit has been validated with various criteria, including sensitivity, specificity, precision, linearity, and recovery. The product instructions are access to more information.

C3 is a central component of the complement system that plays a vital role in the innate defense against common pathogens. C3 primarily derives from the liver, but C3 is also found in the extravascular space. The expression of C3 in hepatocytes is regulated by C/EBPδ and Farnesoid X receptor transcription factors. C3 in the extravascular space is involved in several biological processes, including embryogenesis, organogenesis, regulation of adaptive immunity, the pathogenesis of graft-versus-host disease, and enhancing tumor growth functions. Studies have shown that malignant ovarian epithelial cells synthesize and secrete C3, which, in turn, leads to complement activation in the tumor microenvironment and increases cancer cell proliferation, invasion, and migration.