CD33 and neoplasm: Recently, Corzo and co-workers isolated CD11b+CD33+CD14− MDSCs from peripheral blood and tissues of head and neck cancer and found that only tumor-resident MDSCs displayed significantly inhibitory effects on PHA-induced T cells proliferation 37], suggesting MDSCs of tumor sites and peripheral lymphoid organs may have distinct function, which indicates that tumor-resident MDSCs might have a more direct clinical relevance and warrants further exploration.