The Eagle Biosciences beta-Defensin-4 ELISA Assay Kit is for the quantification of BD-4/β-Defensin-4 in serum, plasma and cell culture supernatant. This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal antibody specific for BD-4/β-Defensin-4 has been pre-coated onto a microtiter plate. Standards or samples are pipetted into the wells and any BD-4/β-Defensin-4 present is bound by the immobilized antibody. After washing away any unbound substances, a biotin conjugated antibody specific for BD-4/β-Defensin-4 and the Streptavidin-HRP Enzyme complex are added to each well and incubate. After washing away any unbound antibody-enzyme reagent, a substrate solution (TMB) is added to the wells and color develops in proportion to the amount of BD-4/β-Defensin-4 bound in the initial step. The color development is stopped by the addition of acid and the intensity of the color is measured at a wavelength of 450 nm ±2 nm. The concentration of BD4/β-Defensin-4 in the sample is then determined by comparing the O.D of samples to the standard curve. Sample Types: serum, plasma, cell culture supernatants. Range: 1.56 - 100 pg/ml. Sensitivity: 0.8 pg/ml. Time: 4 hours ? Defensins form a family of microbicidal and cytotoxic peptides made by neutrophils. Members of the defensin family are highly similar in protein sequence. This gene encodes defensin, beta 4, an antibiotic peptide, which is locally regulated by inflammation.