The Quantikine Rat IL-4 Immunoassay is a 4.5 hour solid phase ELISA designed to measure rat IL-4 levels in cell culture supernates and serum. It contains E. coli-expressed recombinant rat IL-4 and antibodies raised against the recombinant factor. This immunoassay has been shown to quantitate the recombinant rat IL-4 accurately. Results obtained using natural rat IL-4 showed dose response curves that were parallel to the standard curves obtained using the recombinant Quantikine kit standards. These results indicate that this kit can be used to determine relative mass values for natural rat IL-4. Range: 15.60 - 1000 pg/mL. Sensitivity: 5 pg/mL. Time: 4.5 hours