To see if the IDO-1+ macrophages/microglia preferentially reside in specific sites in murine model and human brains, we adopted a thick-section staining method to localize IDO-1+ macrophages/microglia in the human brain, human GBM tissues, and the brains from the APP/PS1 mouse and quinolinic acid models with IBA-1 or GFAP and IDO-1 antibodies. This evidence concerns the gene IDO1 and glioblastoma.