CD8A and juvenile idiopathic arthritis: We previously demonstrated the enrichment of IL‐17A–expressing CD8+ T (Tc17) cells in the synovial fluid (SF) of patients with PsA 10; Tc17 cells have also been observed in the SF of patients with juvenile idiopathic arthritis (JIA) 11 and at the site of inflammation in other immune‐mediated inflammatory diseases (for review, see refs. 2 and 12).