Figure 3.

The presence of GAM within the microenvironment impact GBM proliferation, and reciprocally GBM cells impact on the infiltration of microglia and migration of macrophages. Within this context, GAMs are forced forwards M2 phenotypes by tumor cells. GBM cells can produce specific factors involved in M2 polarization. A recent mechanism involves the YKL40 production in inducing M2 polarization of GAM acquiring immunosuppressive and tumor supporting features. In this context, CD8+ effector TILs can recognize GBM cells. When activated, effector TILs produce IFNγ, previously described as involved in the PD-L1 overexpression of the surface of tumor cells. CD8+ TILs recognizing tumor cells are induced in a dysfunctional state and upregulate the markers related to a late dysfunction. In parallel, the M2-GAMs influence the shift of Th1 to Th2 subtype.