However, in RA patients, the relationships among serum IL-2 levels and disease activity, Th17/Treg immune balance, peripheral blood lymphocyte subpopulation counts, RA-specific autoantibodies such as rheumatoid factor (RF) and anticyclic citrullinated peptide (CCP), and serum levels of other cytokines have rarely been reported. Here, IL2 is linked to rheumatoid arthritis.