Single-cell atlas of the immune microenvironment in MM. (A) Disease course in 3 patients with MM with the extramedullary disease. (B) Analysis of cell clusters using UMAP, showing the annotation and color codes for cell types in extramedullary sites; (left) 37 731 cells color-coded based on cell type; (right) 37 731 cells color-coded by sample. (C) Proportion of cell types in the BM and PB of 3 patients with MM. (D) UMAP plot of immune cell subsets in the myeloma microenvironment. Red: regulatory T cells; green: γδ T cells; orange: CD8⁺ effector T cells; and blue: naive T cells. (E) T-cell subtypes in the BM, ME, and PB of 3 patients with MM. (F) DEGs in 4 T-cell subtypes. ASCT, autologous stem cell transplantation; NMPs, neuromesodermal progenitors; PMCs, pleural mesothelial cells.