ADA2 and systemic-onset juvenile idiopathic arthritis: Moreover, studies showed that ADA2 activities were increased in tubercular pleural effusion, tubercular cerebrospinal fluid, and several autoimmune diseases, such as systemic lupus erythematosus (SLE), autoimmune liver disease (AILD), and macrophage activation syndrome of systemic juvenile idiopathic arthritis (sJIA) (10–13).