The Quantikine HS Human IL-4 Immunoassay is a 6.5 hour solid phase ELISA designed to measure IL-4 levels in cell culture supernates and serum. It contains E. coli-expressed recombinant human IL-4 and antibodies raised against the recombinant factor. This immunoassay has been shown to quantitate the recombinant human IL-4 accurately. Results obtained using natural human IL-4 showed linear curves that were parallel to the standard curves obtained using the Quantikine HS kit standards. These results indicate that this kit can be used to determine relative mass values for natural human IL-4. Range: 0.25 - 16 pg/mL. Sensitivity: 0.22 pg/mL. Time: 6.5 hours