Early work from our laboratory and independent groups identified a progressive increase in the numbers of CD25+FoxP3+ Treg with WHO grade II, III, and IV (GBM) astrocytoma, respectively, either in the peripheral circulation or within the tumor of human resected gliomas (Fecci et al., 2006a; El Andaloussi and Lesniak, 2007; Heimberger et al., 2008a). The gene discussed is IL2RA; the disease is central nervous system cancer.