Macrophage migration inhibitory activity originally identified 30 years ago based on the ability to prevent the migration of guinea pig macrophages out of capillary tubes in vitro. A number of cytokines, including interferon-g and IL-4, exhibit macrophage migration inhibitory activity. A cDNA clone was isolated from a lectin-stimulated T-cell hybridoma cDNA library and reported to encode a protein with macrophage migration inhibitory activity. This protein was referred to as human migration inhibitory factor (MIF). MIF cDNA encodes a 115 amino acid residue polypeptide that lacks conventional hydrophobic leader sequence. MIF is expressed in many tissues and in all cell lines examined to date. MIF was also discovered as a growth factor-induced delayed early response gene DER6. Recently, MIF was reported to be a secreted cytokine that exerts a central and wide ranging role in host inflammatory responses. Evidence for a receptor of this has not been reported. E. coli-expressed MIF lacks macrophage migration inhibitory activity and is recommended for use as a calibrator for MIF immunoassays. E. coli-derived recombinant protein corresponding to Pro2-Ala115 from human MIF, with an N-terminal Met Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile PBS, > 0.1% BSA or HSA. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
