Autoimmune encephalitis is a recently recognized etiology of encephalitis which is mediated by various autoantibodies targeting neural cells or synapses. The responses to immunotherapy is generally good, considerable proportion of patients with autoimmune encephalitis have unfavorable clinical outcomes. Recently, depletion of regulatory T cell (Treg cell) is reported in variable autoimmune diseases and multiple studies have shown that low-dose interleukin-2(IL-2) specifically activates Treg cells to control autoimmunity and inflammation.