Fig. 4: Antigen presentation of CNS and tumor neoantigen drives T_reg cell polarization in the skull bone marrow.

a, Experimental design for profiling of antigen uptake and processing via ICM injections of exogenous peptides. b, Flow cytometry histograms of MHC-II Eα immunoreactivity in FACS-isolated CD4⁺ T cells, B cells, dendritic cells and HSPCs from tibia and skull bone marrow after Eα peptide immunization (500 µg ml⁻¹ i.v., 5 h). c, Quantification of MHC-Eα⁺ cells by genotype with or without anti-MHC-II antibody (n = 3, 10 mice per replicate; mean ± s.e.m.; one-way ANOVA with Šídák’s test). d, Proportions of DQ-OVA⁺ cells in tumor and nontumor mice following ICM injection of DQ-OVA for 2 h (n = 5, 10 mice per replicate; mean ± s.e.m.; one-way ANOVA with Šídák’s test). e, Experimental design for ex vivo peptide pulsing with vehicle or OVA_323–339. f, T cell activation (CD44⁺ cells) after coculture of skull- or tibia-derived dendritic cells, CD8⁺ T cells and HSPCs with OT-II CD4⁺ T cells (n = 5, 10 pooled mice per replicate; mean ± s.e.m.; one-way ANOVA with Šídák’s test). g, FOXP3 expression in vehicle or OVA-immunized dendritic cells, CD8⁺ T cells and HSPCs after OT-II CD4⁺ T cell coculture (n = 5). h, Experimental design for intrathecal injection of aCSF, MOG_35–55 or Fus1_210–24. i, FOXP3 expression in skull CD4 T cells in immunized mice 14 days after injection with aCSF, MOG_35–55 or Fus1_210–24. j, Quantification of skull CD4⁺IFNγ⁺ T cells following intrathecal injection in tumor-bearing or control mice (n = 4 per group, 2 independent experiments). MFI, mean fluorescence intensity. Illustrations in a, e and h created with BioRender.com.