IL2 and vasculitis: Our previous trials in patients with lupus showed that 1 million IU of IL-2 was efficient and safe.5,21 A dose of 1 million IU was chosen because it falls within the range used in recent clinical studies to treat hepatitis C virus–induced vasculitis (1.5-3.0 million IU), graft-vs-host disease (0.3-3.0 million IU per square meter of body surface area), and type 1 diabetes (0.33-3.00 million IU).22,23,24