In GBMs, up-regulated CSF2 production, as indicated herein and in previous studies, promotes immunosuppressive activity of tumour-infiltrating myeloid cells.38,48 Moreover, CSF2 contributes to systemic immune deficits due to generation of neutrophilia and lymphopenia in GBM patients.48,49 Immunosuppressive myeloid cells in glioma microenvironment constitute a barrier to emerging immunotherapies. This evidence concerns the gene CSF2 and lymphopenia.