T cell abnormalities detected in MS include an increased number of circulating CD4+ Th1 and Th17 cells with enhanced effector functions [22,23], insufficient function of regulatory T cells, decreased expression of forkhead box protein P3 (FOXP3) by regulatory T cells [24], and the resistance of CNS-specific effector T cells to regulatory T cell-mediated regulation [25]. This evidence concerns the gene FOXP3 and myeloid sarcoma.