title: Studies on human migration inhibitory factor: characterization of three molecular species.
abstract: Human migration inhibitory factor (MIF), obtained from supernatants of peripheral blood mononuclear cells stimulated with concanavalin A, was analyzed by gel filtration, isoelectrofocusing, and CsCl density gradient centrifugation. A distinct pattern of heterogeneity was determined on the basis of its harvesting time and biochemical criteria. Supernatants from cells cultured for 1 day contained a single peak of MIF activity with an isoelectric point of 4.3 to 5.2, an apparent m.w. of 23,000, and a density of 1.314 g/ml, the same as the density of the marker protein, 125I-HSA (1st day pH 5-MIF). Furthermore, this species of human MIF was sensitive to treatment with trypsin, strongly suggesting its being a protein, but not to treatment with neuraminidase and corresponds therefore to guinea pig pH 5-MIF. However, when 2nd day supernatants were analyzed under the same conditions, 2 MIF species were found. One species with an isoelectric point of 2.4 to 3.3 had an apparent m.w. of 65,000 (2nd day 3-MIF). The other species with an isoelectric point of 4.3 to 5.6 had an apparent m.w. of 23-43,000 (2nd day pH 5-MIF). Upon centrifugation in CsCl density gradients, the density (rho 25 of 1.314 to 1.414 g/ml) of both species was found to be greater than that of the pure protein, 125I-HSA. In addition, both species were chymotrypsin and neuraminidase sensitive but not trypsin sensitive, further suggesting their glycoprotein nature.
mesh_terms: D000818:Animals; D002500:Centrifugation, Isopycnic; D002850:Chromatography, Gel; D010450:Endopeptidases / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D007525:Isoelectric Focusing; D008263:Macrophage Migration-Inhibitory Factors; D008970:Molecular Weight; D009439:Neuraminidase / Q000494:pharmacology; D013997:Time Factors; D014357:Trypsin / Q000494:pharmacology
chemical_list: D008263:Macrophage Migration-Inhibitory Factors; D009439:Neuraminidase; D010450:Endopeptidases; D014357:Trypsin