In diseases in which patients present with high baseline IL-38, a reduction of IL-38 after treatment is a predictor for treatment response in e.g., reperfusion therapy in myocardial infarction (23), in treatment of rheumatoid arthritis (25), and in juvenile SLE patients treatment with prednisone reduced IL-38 concentrations (48). The gene discussed is IL1F10; the disease is systemic lupus erythematosus.