In human cancer patients, similar subsets of MDSCs exist and are characterised by different surface markers along with reduced human leukocyte antigen-DR isotype (HLA-DR) expression, namely CD3–CD19–CD56–CD11b+CD14+CD15–CD33+HLA-DRlow/– M-MDSCs, and CD3–CD19–CD56–CD11b+ CD14–CD15+CD33+HLA-DRlow/– G-MDSCs. This evidence concerns the gene CD33 and cancer.