CCL2 and myeloid sarcoma: In the present study, the lower level of expression of CCR2 on infiltrating macrophages in EAE lesions as compared to CCR1 and CCR5, as well as the recent demonstration that CCR2 expressing cells are infrequent in MS lesions [59], may be explained by data from a recent study by Mahad et al [58,60], who used an in vitro model of the blood-brain barrier to demonstrate that T cells and monocytes rapidly down-regulate CCR2 while transmigrating across the barrier in response to presented CCL2.