The issue of Tregs functionality is especially relevant since several studies have shown that CD4+CD25+ Treg cells are increased in inflammatory sites in autoimmunity (i.e. pancreatic islets in diabetes, synovia of arthritic joints [9] and, recently, in CSF of MS patients [10] raising the question of whether these cells are functional at these locations. The gene discussed is CD4; the disease is myeloid sarcoma.