Fig. 3. Characterization of MDSC and CD138⁺ MM cells in BMMC or PBMC from patients with MGUS, SMM, or MM and healthy donors.

Freshly isolated BMMC or PBMC from patients with MGUS (BM: N = 5, PB: N = 5), SMM (BM: N = 5, PB: N = 5), newly diagnosed MM (BM: N = 5, PB: N = 5), relapsed MM (BM: N = 5, PB: N = 5), relapsed/refractory MM (BM: N = 5, PB: N = 5), and healthy donors (BM: N = 4, PB: N = 5) were evaluated for the frequency of MDSC or CD138⁺ MM cells and their expression of immune checkpoints. A MM patients BMMC had significantly (*p < 0.05) higher G-type MDSC (CD11b⁺ CD33⁺ HLA-DR^low/− CD14⁻ CD15⁺), but not M-type MDSC (CD11b⁺ CD33⁺ HLA-DR^low/− CD14⁺ CD15⁻), compared to MGUS/SMM patients or healthy individuals. B G-type MDSC from MM patients BMMC and PBMC expressed significantly (*p < 0.05) higher PD-L1, but not PD-L2 or LAG3, than MGUS and SMM patients or healthy individuals. C CD138⁺ tumor cells in MM patient BMMC have significantly (*p < 0.05) higher PD-L1, but not PD-L2, expression as compared to BMMC from healthy individuals.