MMP2 and myeloid sarcoma: In conclusion, our study demonstrated that the disruption of the BBB caused by the humoral factors present in the sera of MS patients involves two differentially regulated mechanisms: one is the disruption of BBB function via the autocrine secretion of MMP-2/9 from BMECs in relapsing MS or the exposure to autoantibodies against BMECs in SPMS, and the other is the up-regulation of VCAM-1 in BMECs by exposure to autoantibodies against BMECs present in MS sera.