We were particularly interested in examining IL-17 production by other cell populations, such as γδ T cells, CD8 T cells and NK cells, but observed that this cytokine was exclusively produced by CD4+ T cells in RA synovial fluid and in the peripheral blood of healthy controls, eRA and established RA patients, consistent with work published by Shen et al [29]. The gene discussed is IL17A; the disease is rheumatoid arthritis.