library_construction_protocol: Single cell suspension of glioma-005 cell line was stereotactically injected into the hippocampus of 8- to 12-week-old C57BL/6J mice. 7 days after tumor implantation, mice were randomly divided into groups and injected with antibodies αCTLA-4 (Syrian hamster clone 9H10), Isotype control antibodies rat IgG2a (clone LTF-2) and depletion antibody aCD4 (clone GK1.5) were administered intraperitoneally (i.p.) . All mice were perfused with ice-cold PBS after euthanasia to reduce the influence of peripheral blood derived cells. All the brains were collected in ice-cold PBS, and then mechanically and enzymatically dissociated using a papain-based neural tissue dissociation kit P (Miltenyi Biotec) supplemented with 0.1% type I collagenase (Thermo Fisher Scientific) in a C-tube (Miltenyi Biotec), and then dissociated with a gentleMACS Qcto Dissociator, followed by filtration with 70 µm cell strainers. Filtered cells were incubated with ACK lysis buffer (Invitrogen) to lyse red blood cells. For immune cell suspension, filtered cells were resuspended in 5 mL 37% Percoll, and slowly added beneath the 70% Percoll, and then centrifuged with brakes off. The immune cells were isolated from the interface of 37% and 70% Percoll and transferred into excessive RPMI 1640 medium containing 10% fetal bovine serum. scRNAseq and scTCRseq were performed in brain harvested T cells from 005 bearing mice treated with IgG or αCTLA-4 (35 days post implantation). CD3+ cells were sorted and immediately loaded onto a 10x Chromium Chip G using reagents from the Chromium Single-Cell 5' Library and Gel Bead Kit v1.1 (10x Genomics) according to the manufacturer's protocol. 5' gene expression libraries were generated using 10X Genomics Chromium Single Cell 5' Library Construction Kits according to manufacturer protocols. TCR enrichment libraries were prepared following mouse T cell Single Cell V(D)J Enrichment Kits (10x Genomics). 10x Chromium Single cell 5' + VDJ Library