HSPC molecular interactions with T cells. (A) UMAP visualization of single T cells derived from bone marrow (triangles) or peripheral blood (circles) from SAA (dark red, n = 4), non-SAA (dark blue, n = 11) or Ctrl (dark gray, n = 2). Colors indicate naïve cells (red), memory cells (green), and effector cells (blue). (B) Top 20 GO terms enriched among the genes upregulated in CD4⁺ T cells from patients with non-SAA (n = 11). Dot color indicates the logarithmic transformed adjusted P value (Benjamini-Hochberg correction). Dot size indicates enrichment score estimated by Metascape. Abbreviation: AP.P.EP, antigen processing and presentation of exogenous peptide. (C) Box plots indicating a significantly increased number of HSPCs molecular interactions with CD4⁺ and CD8⁺ T cells in non-SAA (HSPCs, n = 12; T cells, n = 11; Student t test). (D) Venn diagram displaying the overlap of molecular interactions between CD4⁺ and CD8⁺ T cells in non-SAA (HSPCs, n = 12; T cells, n = 11). (E) Number of non-SAA–specific molecular interactions in each T-cell subset and HSPCs. Gradient color and dot size indicate relative abundance of molecular interactions. (F) Spectrum of ligand-receptor pairs (rows) between HSPCs and T cells (columns) as observed in patients with non-SAA (HSPCs, n = 12; T cells, n = 11). Dot sizes and colors represent logarithmic transformed P values (permutation test) and mean expression of interacting molecules in corresponding cell subsets. (G) Average expression of apoptosis signaling genes and critical components in this signaling pathway. *P ≤ .05; **P ≤ .01; ***P ≤ .001; Wilcoxon rank-sum test. (H) Average expression of CCR5 pathway genes and critical components in this signaling pathway. (I) Average expression of upregulated genes in proinflammatory monocytes in autoimmune disease.