We next evaluated in detail the composition of blood monocytes to discriminate the three main subsets that are classical monocytes (C=CD14+/CD16−), intermediate (I=CD14+/CD16+) and non-classical subsets (NC=CD14−/CD16+) (Fig. 6b), and further analyzed the expression of CCR2 on their surface (Fig. 6d), as it is known that CCL2 chemokine promotes monocyte accumulation at the tumor site, and has already been implicated in the recruitment of myeloid cells in glioma [28, 29]. Here, CCL2 is linked to central nervous system cancer.