PDCD1 and brain neoplasm: Because activating TLR3 receptors activates interferon secretion by dendritic cells [21–24] and interferon signaling results in changes in the expression of PD-1 ligands we sought to characterize the expression of PD-L1 and PD-L2 in the different sets of myeloid cells infiltrating the brain tumors and also in the peripheral lymphoid organs [5, 25].