We have now developed a simple and robust method to generate CD11b+/CD14+/HLA-DR- /CD15- monocytic MDSCs from normal monocytes through culture in human glioma-conditioned media and confirmed that the frequency of these cells can be approximated (though slightly over-estimated) by determining the frequency of CD14+/HLA-DR- cells (Fig 1). Here, CD14 is linked to central nervous system cancer.