Methods are provided for reducing the activity or function of an inflammatory cell by contacting a cell with, or administering to a subject in need thereof, an effective amount of a circumsporozoite protein or homolog thereof, or a fragment thereof. Methods of treating an inflammatory disease, or an autoimmune disease or for inducing tolerance are also disclosed as are pharmaceutical compositions comprising a therapeutically effective amount of a circumsporozoite protein or homolog thereof, or a fragment thereof and a pharmaceutically acceptable carrier.