IL2 and systemic lupus erythematosus: In a clinical study involving patients with refractory SLE—defined as those with persistent disease activity despite high-dose glucocorticoids and/or cytotoxic drugs—the combination of Low-dose IL-2 (100 WIU, 3–5 days/month) and rapamycin(0.5 mg every other day) demonstrated synergistic effects (272).