However, less is known about the contribution of specific innate cell populations to perpetuate chronic inflammation and the induction of pathogenic CD4+ T cells able to produce both IL-17 and IFN-γ (known as Th1/Th17 cells), a T cell subset that is enriched in synovial fluid (SF) of patients with RA (7) and has been linked to severity of multiple autoimmune disorders (8–10). Here, CD4 is linked to rheumatoid arthritis.