IL-15 down-regulated NKp46 expression on NK cells from both RA patients (58.5 ± 3.8% vs. 67.1 ± 3.5%, p < 0.001) and healthy controls (70.1 ± 2.9% vs. 78.7 ± 2.6%, p = 0.001). This evidence concerns the gene IL15 and rheumatoid arthritis.