Circulating PMN-MDSCs (identified as CD11b+CD33+HLA-DR−/lowCD14−CD15+LOX1+ cells) and M-MDSCs (CD11b+CD33+HLA-DR−/lowCD14+CD15− cells) [29], yet MDSCs have been little studied in MS and there is conflicting data as to the cell type most strongly involved or altered during the clinical course of MS [30–32]. This evidence concerns the gene CD33 and myeloid sarcoma.