IL15 and systemic lupus erythematosus: IL-15 increased NK cytotoxicity of active SLE patients and inactive SLE, but to a lesser extent compared to IL-15-treated controls (inactive SLE, 20.1±4.0% vs. 5.1±1.2%, p = 0.003, and active SLE 13.8±2.9% vs. 3.8±0.8%, p<0.001).