CCR7 and myeloid sarcoma: In addition, FTY720 primarily reduced the numbers of CCR7+ CD45RA+ naïve T cells and CCR7+ CD45RA− central memory T cells in the blood in MS patients, because these T cells express the homing receptor CCR7, recirculate through the lymph nodes, and can be sequestered into the lymph nodes by FTY720 [43,50].