Glycolipid affinity purification of migration inhibitory factor.

Abstract

Migration inhibitory factor (MIF) is an immune mediator secreted by primed lymphocytes on in vitro challenge by antigen or mitogen, which elicits various physiological responses from its target cell, the macrophage1,2. Previous studies suggest that membrane glycoconjugates have an important role in regulating the interaction between MIF and the macrophage. A macrophage glycolipid functions as a putative receptor for MIF as evidenced by its ability to enhance the macrophage response to MIF3,4. This enhancing ability of glycolipids requires the presence of sialic acid5 and fucose6; these carbohydrate residues are also required on the macrophage surface for the induction of an intact response by MIF5,7. Furthermore, it has been reported4 that incubating a preparation of mixed gangliosides from bovine brain with lymphocyte supernatants abolished their MIF and macrophage activating factor (MAF) activities. Taken together, these results are evidence that a glycolipid serves as a membrane receptor for MIF. We predict that glycolipids which enhance the macrophage response to MIF, also bind MIF with subsequent elution of biological activity, and present here evidence in support of this notion. We also demonstrate that glycolipid covalently bound to agarose provides a novel means of affinity purification of MIF.