The present invention relates to a process for ameliorating or preventing diseases that are caused, in part, by an increased level of, and/or an abnormal responsivity to, interferon. Alzheimer's disease, HIV infection, Down syndrome, transplant rejection, autoimmune disease, and infant encephalitis are examples of such diseases. Specifically, the invention provides a method for treating subjects suffering from, or at risk for, such diseases by the administration of a pharmacological preparation of interferon binding proteins of mammalian and/or viral origin that antagonize interferon's action. This invention comprises compositions of interferon binding proteins that can inhibit the activity of interferon gamma plus interferon alpha such compositions along with their method of production and modification being described herein.