The Quantikine Human LIF Immunoassay is a 3.5 or 4.5 hour solid phase ELISA designed to measure soluble human LIF in cell culture supernates, serum, and plasma. It contains E. coli-expressed recombinant human LIF and antibodies raised against the recombinant factor. This immunoassay has been shown to quantitate the recombinant LIF accurately. Results obtained measuring natural human LIF 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 human LIF. Range: 31.20 - 2000 pg/mL. Sensitivity: 8 pg/mL. Time: 3.5 hours or 4.5 hours