Interleukin-2 Deficiency Associated with Renal Impairment in Systemic Lupus Erythematosus

Impaired interleukin-2 (IL-2) production was reported in systemic lupus erythematosus (SLE). The aim of this study was to investigate the clinical relevance of serum IL-2 and therapeutic effects of recombinant IL-2 (rIL-2) in SLE, especially in lupus nephritis (LN). Decreased serum IL-2 was found in patients with active LN (P = 0.014) and correlated with 24-h urine protein excretion (r = -0.281, P = 0.026). Compared with LN patients with decreased levels of serum IL-2, patients with increased levels had better remission rate (P = 0.041). Furthermore, patients with exogenous low-dose IL-2 supplement demonstrated better improved nephritis and higher remission rate (55.56%, P = 0.058) than those with conventional therapy. In addition, the percentages of regulator T (Treg) cells expanded in LN patients with low-dose recombinant human IL-2 treatment (P = 0.007), especially in LN patients achieving remission (P = 0.010). IL-2 deficiency is associated with renal impairment that can be improved by exogenous IL-2 supplement.