The Quantikine Human IL-6 sR Immunoassay is a 4.5 hour solid phase ELISA designed to measure human IL-6 sR in cell culture supernates, serum, plasma, and urine. It contains recombinant human IL-6 sR produced in Sf 21 cells and antibodies raised against this protein. This kit has been shown to accurately quantitate the recombinant soluble IL-6 R. Results obtained using natural IL-6 sR 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 IL-6 sR. Since the measurement of human IL-6 sR by this immunoassay is insensitive to added recombinant human IL-6, it is probable that this measurement corresponds to the total amount of the soluble receptor present in samples ( i.e. the total amount of free receptor plus the total amount of receptor bound to IL-6). Range: 31.20 - 2000 pg/mL. Sensitivity: 15.1 pg/mL. Time: 4.5 hours