Systemic lupus erythematosus (SLE) is a potentially life-threatening autoimmune disease characterized by altered balance of activity between effector and regulatory CD4(+) T cells. The homeostasis of CD4(+) T cell subsets is regulated by interleukin (IL)-2, and reduced production of IL-2 by T cells is observed in individuals with SLE. Here we report that treatment with low-dose recombinant human IL-2 selectively modulated the abundance of regulatory T (Treg) cells, follicular helper T (TFH) cells and IL-17-producing helper T (TH17) cells, but not TH1 or TH2 cells, accompanied by marked reductions of disease activity in patients with SLE.