Human MDSC were isolated by magnetic bead column separation after one-week co-culture with SCCL-MT1 or USC-HN2 HNSCC cell lines (CD33+) or MCF-7 breast cancer cell line (CD11b+) and non-suppressive CD33+ or CD11b+ control cells were isolated from medium only PBMC cultures. Here, CD33 is linked to head and neck squamous cell carcinoma.