Some patients with autoimmune and inflammatory diseases treated with intravenous immunoglobulin G (IVIg) as a first line therapy are refractory. Identification of predictive biomarker(s) to segregate responders and non-responders to IVIg therapy remains critical. A number of biomarkers, particularly in Kawasaki disease, have shown potential for predicting response to IVIg. © 2015 Elsevier Ltd.