this invention relates to methods for inhibiting the initiation or progression of a pathologic disorder associated with atherosclerotic plaque formation comprising administering to a subject an amount of il - 9 sufficient to inhibit plaque formation and / or plaque progression and / or to promote plaque regression . the methods of this invention also relate to inhibiting the proliferation of smooth muscle cells in one or more arteries and to inhibiting the deposition and accumulation of fat and proteins in one or more arteries .