However, it is well possible that exhausted T cells further upregulate CD39, which would be concordant with the results presented by Gupta et al. Two previous studies also observed accumulation of Foxp3—CD39+ CD4+ and CD8+ T cells and of CD73—CD8+ T cells in the synovia of JIA patients [27, 43]. This evidence concerns the gene ENTPD1 and juvenile idiopathic arthritis.