Effect of BM DCs on tumor plasma cell susceptibility to CD8⁺ T cell–mediated killing in vitro. Representative plots and percentages (mean and standard deviation) of lysis of CFSE-labeled tumor plasma cells by BM CD8⁺ T cells from 15 MM patients. Immunomagnetically purified CFSE-labeled plasma cells were cultured with autologous BM mDCs in different conditions. After a preincubation period, Far Red–labeled K562 cells and autologous BM CD8⁺ T cells were added to each well at the indicated ratios. Far Red–labeled K562 cells were used as negative control targets.