Saadoun et al.19 evaluated the clinical efficacy and immunologic response after low-dose IL-2 therapy in HCV-related vasculitis patients, and found that treatment resulted in a 3 median folds increase of the numbers of CD4+ Treg cells and a 8 median folds increase of CD8+ Treg cells in peripheral blood, as well as a small increase in NK and CD56bright NK cells, but decrease of B cells. This evidence concerns the gene IL2 and vasculitis.