In contrast to that observed with cell percentages, addition of IL-15 alone enhanced the iNKT cell recovery ratio in controls (14.7±9.9 vs. 1.1±0.2, p = 0.013) and SLE patients (7.4±3.0 vs. 1.2±0.4, p = 0.001) as well. This evidence concerns the gene IL15 and systemic lupus erythematosus.