These drugs have been shown to favorably alter the natural history of relapsing remitting MS by slowing the progression of disability, reducing relapse rate, and decreasing brain inflammation as measured by MRI. There is evidence that the treatment effects of both IFN-beta and glatiramer acetate are related to their properties in regulating various components of the immune system, in particular, the T cell functions (e.g. proliferation and migratory behavior) and cytokine production.