CD4 and central nervous system cancer: We found that CD8+ T cells, gamma delta T cells, M0 macrophages, M1 macrophages, M2 macrophages, and neutrophils infiltrated obviously more in glioma tissue, with Siglec15 being highly expressed, and resting memory CD4+ T cells, monocytes and activated mast cells remained markedly enriched in the low Siglec15 group.