Comparsion of the properties of two antigen-induced guinea pig lymphokines

The properties of macrophage migration inhibition factor (MIF) and mitogenic factor (MF) were compared using culture supernatants of antigen-stimulated lymph node cells from inbred guinea pigs. Gel filtration on Sephadex G-100 indicated molecular weights of about 60,000 and 25,000 for MIF and MF, respectively. The lymphokines also differed with respect to heat sensitivity, MIF being largely inactivated by 60 degrees C for 20 min, whereas MF was unaffected by this treatment. The time course of production, antigen specificity of induction, and susceptibility to neuraminidase were also examined.