Induction of multiple myeloma-specific cytotoxic T lymphocyte stimulation by dendritic cell pulsing with purified and optimized myeloma cell lysates

We investigated the possibility of immunotherapy for multiple myeloma (MM) using myeloma-specific cytotoxic T lymphocytes (CTLs) that were stimulated in vitro by dendritic cells (DCs) pulsing with purified and optimized myeloma lysates. CD14⁺ cells were cultured in the presence of GM-CSF and IL-4. On day 6, the immature DCs were pulsed with the purified myeloma cell lysates, and then maturation of the DCs was induced by the addition of a cytokine cocktail. There were no differences in the phenotypic expressions of mature DCs that were generated by pulsing with CD138⁺ cell lysates or total cell lysates. In optimization of the concentration of myeloma lysates, DCs pulsed with 10 μg/mL of myeloma lysate had greater allogeneic T-cell stimulatory capacities than those pulsed with higher concentrations of myeloma lysates. The CTL lines generated by DCs pulsed with myeloma lysates demonstrated potent cytotoxic activities against autologous target cells, but not against HLA-A2^- cell lines or K562 cell lines. The DCs pulsed with myeloma lysates demonstrated a higher stimulatory capacity for autologous CTL compared with mature nonpulsed DCs. These results suggested that the DCs pulsed with purified and optimized myeloma cell lysates could generate potent myeloma-specific CTLs for approaches in MM.