FCGR2B and autoimmune thrombocytopenic purpura: Upregulation of FcγRIIB has also not been observed following IVIg treatment of human monocytes and macrophages isolated from peripheral blood of healthy donors [209], nor from patients with Kawasaki disease [357] or ITP [358], despite the fact that Kawasaki disease and ITP patients typically benefit from IVIg treatment.