An interesting piece of data that has contributed to paving the way to the study of the role of CTLA-4 and of other immune checkpoints in the pathogenesis of MS concerns the fact that several immune checkpoint inhibitors, including CTLA-4 inhibitors, could trigger or exacerbate certain immune mediated diseases, including MS [53,54,55,56,57,58,59]. Here, CTLA4 is linked to myeloid sarcoma.