CD11b⁺ myeloid cells from BM and FLs from patients with MM, and HBM. (A) Samples from patients with NDMM (n = 6), RRMM (n = 7) (BM and FLs), and from HBM (n = 3) are shown in the UMAP representation of 105 192 CD11b⁺ cells captured with 10× V3 5ʹ scRNA-seq (see “Materials and methods” for complete details). Nine clusters observed were: (1) TREM⁺MME⁺ mature neutrophils, (2) S100A8⁺CD14⁺ macrophages (Mϕ), (3) S100A8/9⁺MMP9⁺ immature neutrophils, (4) LTF⁺CAMP⁺ immature neutrophils, (5) S100A8⁺LTF⁺ immature neutrophils, (6) TNFAIP3⁺CXCL8⁺ mature neutrophils, (7) RETN⁺LCN2⁺ mature neutrophils, (8) Mki67⁺DEFA3⁺ preneutrophils, and (9) HLA-DR⁺CD16⁺ macrophages. Bottom panels represent cell contributions from HBM (left), NDMM (middle), and RRMM (right). (B) UMAP representation of CD11b⁺ cells observed. The contribution of BM-derived cells (n = 59 861 cells) is shown in blue. The contribution of FL-derived cells (n = 45 331 cells) is shown in red. (C) Scaled bar graph representation of each cell type contribution (y-axis) from healthy donors and patients with MM (x-axis; n = 16). Color convention as per panel A. Top panel, cell type distribution from BM cells; bottom panel, cell type distribution from FLs (1 sample without cells). (D) Scaled normalized heat map of top 10 transcripts associated with each cluster. Sample downsized to 5000 cells per cluster. Blue represents downregulated genes, and red represents upregulated (log₂ fold-change) genes in cell types shown at top.