Figure 3.

Flow cytometric analysis of perforin expression in NK cells and cytotoxic CD8⁺ cells. (a) Normal control: 95% of NK cells and 14% of CD8⁺ cells are perforin-positive. (b) A patient with systemic juvenile rheumatoid arthritis (sJRA) with a normal pattern of perforin expression: normal mean channel fluorescence (MCF) in NK cells with 92% of NK cells and 10% of CD8⁺ T cells being perforin-positive (this pattern was observed in all controls, in 18 of 20 other JRA patients, and in 15 of 20 sJRA patients). (c) A patient with sJRA with low MCF in NK cells and mildly decreased proportions of perforin-positive NK cells (74%) and CD8⁺ T lymphocytes (5%) (this pattern was observed in 2 of 20 other JRA patients and in 5 of 20 sJRA patients). (d) A patient with sJRA with low MCF in NK cells and very low proportions of perforin-positive NK cells (20%) and no perforin-positive CD8⁺ T lymphocytes (observed in 1 of 20 sJRA patients only).