title: Purification of thymic macrophage migration inhibitory factor (MIF).
abstract: Aqueous extracts of the thymus of animals which had been challenged immunologically have been shown to contain MIF activity. This MIF could be purified by precipitation with 70% ethanol, concentrated by ultrafiltration between 30,000 and 50,000 daltons, isoelectrically focused at pH 6.8-7.1, and electrophoresed on preparative acrylamide gels. The resulting product is electrophoretically homogeneous at pH 4.3 in polyacrylamide-gel electrophoresis and SDS-gel electrophoresis. It has a molecular weight of 36,000 daltons. It is trypsin- and neuraminidase-labile and is thermostable. It degrades and reassembles in electrophoresis at pH 7.0. It is not chemotactic for macrophages but apparently activates them phagocytically. It has no proteolytic activity.
authors.affiliation: Biochemical Research Laboratory, Research Foundation of Children's Hospital, National Medical Center, Washington, D.C..
authors.forename: J C
authors.initials: JC
authors.lastname: Houck
authors.forename: C M
authors.initials: CM
authors.lastname: Chang