The Quantikine Human IL-1ra Immunoassay is a 4.5 hour solid phase ELISA designed to measure IL-1ra in cell culture supernates, serum, and plasma. It contains E. coli-derived recombinant human IL-1ra as well as antibodies raised against the recombinant factor. This immunoassay has been shown to accurately quantitate recombinant human IL-1ra. Results obtained using natural human IL-1ra showed linear curves that were parallel to the standard curves obtained using the Quantikine kit standards. These results indicate that this kit can be used to determine relative mass values for natural human IL-1ra. Range: 31.20 - 2000 pg/mL. Sensitivity: 18.3 pg/mL. Time: 4.5 hours