Enrichment of Th17-1 cells in the bone marrow of patients with myeloma. Paired samples from blood and bone marrow of patients with plasma cell dyscrasias were stimulated with PMA/ionomycin for 5 hours in the presence of GolgiStop. The presence of IL17-producing cells were examined by intracellular flow cytometry. The cells were labeled with aqua LIVE/DEAD dye to gate out the dead cells, fixed and permeabilized, and stained with antibodies against CD3, CD4, CD8, IL17, IL2, and IFNγ. (A) Frequency of IL17-producing cells in the blood compared with the bone marrow. Open symbols indicate MGUS; closed symbols, myeloma. P < .05 Horizontal bars represent the mean for IL17 cells in blood and marrow. (B) Proportion of the IL17-producing cells producing IFNγ (Th17-1 cells) in the blood or marrow of patients with myeloma (n = 4) and MGUS (n = 4). *P < .05 for marrow versus blood in myeloma, and for MGUS marrow versus myeloma marrow. (C) Representative fluorescence-activated cell sorter (FACS) plot showing frequency of Th17 as well as Th17-1 cells in paired blood and marrow samples from patients with myeloma or MGUS. The numbers represent the percentage of IL17-producing CD3⁺ T cells. (D) Comparison of the proportion of Th17-1 cells in patients with or without lytic bone disease. Error bars represent the mean and standard deviation.