Figure 2

Flow cytometric analysis of CD56^bright and CD56^dim natural killer cells. (a) In healthy individuals, most circulating NK cells are CD56^dim (about 90%) and express high levels of perforin. In contrast, CD56^bright NK cells comprise about 10% of all human NK cells and express low levels of perforin. (b, c) Two distinct patterns of CD56 staining observed in patients with systemic juvenile rheumatoid arthritis (sJRA): (b) normal pattern (observed in 17 of 20 patients with sJRA as well as in all controls, and all other JRA patients); (c) almost complete disappearance of CD56^bright subset of NK cells (observed in 3 of 20 patients with sJRA only).