Indeed, we confirmed previously reported [7] inversion of the CD4+:CD4− T-cell ratio within SF compared to blood (SF 0.90 ± 0.16, HC PB 1.75 ± 0.15, JIA PB 1.63 ± 0.07, Fig. 4C) [7]. Here, CD4 is linked to juvenile idiopathic arthritis.