Interestingly, when brain tissue was examined from 16 untreated MS patients, no Tregs were found in 30% of the biopsies, and the number of FoxP3+ cells was generally low in the brain tissue[37] suggesting Tregs may not be capable of infiltrating the CNS in MS patients, and therefore, immune responses are un-regulated. This evidence concerns the gene FOXP3 and myeloid sarcoma.