scRNA-seq analysis reveals potential mechanisms by which Tumor-associated myeloid cells support T-ALL in the CNS. (A) UMAP projection of scRNA-seq data showing 7748 myeloid and lymphoid cells from the CNS of healthy and leukemic mice, including annotated transcriptionally distinct cell subsets. (B) UMAP projection, similar to panel A, with cells differentially colored by tumor status: healthy (blue) and leukemic (red). (C) Heat map showing significantly (P < .05) differentially expressed genes (DEGs), filtered for Area Under the Receiver Operating Characteristic (AUROC) curve values <0.35 or >0.65, indicating genes downregulated or upregulated, respectively, by the indicated myeloid subsets in the leukemic vs healthy CNS. MSigDB Hallmark pathways that were enriched for DEGs from all 3 tumor vs healthy myeloid subsets are denoted to the left of the heat map (Interferon_Alpha_Response [“Interferon Alpha”], Interferon_Gamma_Response [“Interferon Gamma”], “OxPhos, and MYC_Targets_V1), with bars indicating genes enriched in each pathway. (D) GSEA of the top 5 upregulated and downregulated MSigDB Hallmark pathways enriched for DEGs between tumor vs healthy myeloid cells of the indicated subsets, ordered by GSEA enrichment score. (E) GSEA of C2_PID pathways including integrins, growth factors, and adhesion molecules that were enriched for DEGs between the indicated tumor vs healthy myeloid subsets or between T-ALL vs healthy T cells in the CNS. Upregulated pathways that include integrins are highlighted in red. (F) Heat map showing relative expression of integrins in the indicated leukemic vs healthy myeloid subsets or in T-ALL vs healthy T cells based on scRNA-seq data. In panels C,F, the color scale indicates the AUROC value; values above or below AUROC of 0.5 indicate upregulation or downregulation in leukemic cells, respectively. ROS, reactive oxygen species; TGF_B, transforming growth factor beta.