IL2 and systemic lupus erythematosus: Based on the area under the receiver operating characteristic (ROC) curve (AUC) of 0.813, the specificity of a low regulatory T cells (Tregs) proportion (≤13.35%) plus skin rash to predict GR to IL-2 therapy was 100%, with a sensitivity of 68.75%.<bold>Conclusion.</bold> A low Treg proportion and skin rash indicate GR to low-dose IL-2 treatment in SLE patients.<bold>Trial registration number</bold> ClinicalTrials.gov Registries ((NCT02465580 and NCT02084238).</p>