KLRB1 and juvenile idiopathic arthritis: As expected and previously described (18), higher frequencies of IFN-γ producing cells (both CD161+ and CD161-), were found in SF than in PB of the JIA patients (Fig 4A), and more importantly we also found a significant increase of TNF-α producing cells (both CD161+ and CD161-), in SF compared to PB (Fig 4A).