We found that novel multipotent DCs were generated with the addition of IL-15, and that these had high expression of adhesion molecules, costimulatory molecules, and migration receptors, as well as abundant secretion of IFN-γ, indicating outstanding activation of T cells, CIK cells, and NK cells, and thus strong cytotoxicity against target myeloma cells. The gene discussed is IFNG; the disease is plasma cell myeloma.