Supporting our hypothesis, the data suggest that intratumoral CD11b + CD45lo resident microglia express significantly lower levels of activating FcγR relative to intratumoral CD11b + CD45hi mononuclear cells, which may account for the inability of anti-GITR (2a) to induce Treg depletion through ADCC in brain tumor. This evidence concerns the gene FCGR2A and brain neoplasm.