IL2 and systemic lupus erythematosus: In addition, exogenous IL-2 at the final concentration of 6 pg/ml and sIL-2Rα at the final concentration of 2500 pg/ml were added in serum from HC (n=7) and SLE patients (n=7), followed by incubating for 1 h and detected by the mixed solid-phase sandwich ELISA system (n=7).