In addition, Ellingsen et al. observed a significant increase of the DPP-IV/CD26 antigen expression in CD4+ T cells only in patients with chronic (median disease duration 11.5 years) rheumatoid arthritis [16], while in RA patients early after diagnosis (<6 months), there were no differences in comparison to healthy controls [30]. This evidence concerns the gene CD4 and rheumatoid arthritis.