Costimulatory molecule expression and cytokine production by BM DCs (from 20 MGUS and 20 MM patients). (A-D) Changes in percentages of mDCs (A-B) and pDCs (C-D) expressing CD80 (A,C) and CD86 (B,D) upon stimulation with apoptotic tumor plasma cells. Wilcoxon signed-rank test. (E-H) IL-12 (E,G) and IFN-α (F,H) production by mDCs and pDCs, respectively, upon stimulation with apoptotic tumor plasma cells, assessed by flow cytometry (E-F) and ELISA (G-H). Mann-Whitney U test. IL-12 and IFN-α protein levels in positive cells analyzed with flow cytometry are reported in MESF units. The MESF rate was calculated as the MESF of the stimulated sample divided by that of the unstimulated sample for the same subject. P values are shown only for statistically significant comparisons.