While the absence of Treg cells in scurfy mice and IPEX (Immune dysregulation, polyendocrinopathy, enteropathy, X-linked) patients bearing a dysfunctional FOXP3 gene leads to severe multisystemic lethal autoimmune disease [1–3], transfer of T cells devoid of Treg cells in nude mice leads to milder systemic autoimmunity, including gastritis, oophoritis and sometimes clinical and biological features resembling systemic lupus erythematosus (SLE), including arthritis, nephritis and the production of anti-double stranded DNA [4–6]. This evidence concerns the gene FOXP3 and systemic lupus erythematosus.