Although CD4+CD25high and CD127low/− cell populations were traditionally used to identify the human Treg subset and Foxp3 is an important and even unique marker for Treg cells [17–19], this is not case for the identification of Treg cells in patients with autoimmune diseases since some activated non-Treg cells also express Foxp3, CD25 and have also lost CD127 [20]. This evidence concerns the gene FOXP3 and autoimmune disease.