Studies on guinea-pig macrophage migration inhibitory factor (MIF). I. Glycoprotein nature and net charge.

Guinea-pig macrophage migration inhibitory factor (MIF), obtained by the stimulation of sensitized lymph node cells with tuberculin PPD, was characterized as a glycoprotein by the following criteria: (a) its activity is destroyed by 0.02 M sodium periodate; (b) when MIF-containing culture fluids are subjected to precipitation by perchloric acid (final concentration 1 M), the inhibitory activity is recovered in the supernatant; and (c) MIF binds to Sepharose-linked concanavalin A and can be eluted with methyl-alpha-D-glucopyranoside. When MIF-containing culture supernatants are fractionated by isoelectrofocussing, migration inhibitory activity is recovered in a fraction with an isoelectric point of 4.4--4.6.