methods and compositions for using the mhc class ii invariant chain polypeptide , ii , as a receptor for macrophage migration inhibitory factor , are disclosed . these include methods and compositions for using this receptor , as well as agonists and antagonists of mif which bind to this receptor , or which otherwise modulate the interaction of mif with cd74 or the consequences of such interaction , in treatment of conditions characterized by locally or systemically altered mif levels , particularly inflammatory conditions and cancer .