Multiple myeloma is a cancer of the antibody-producing white blood cells. Stem cell transplantation from a suitable donor can cure the disease. However, to establish an optimal curative effect, donor's T cells, which eliminate the cancer cells, must be activated by specialized cells of the recipient. However, in many myeloma patients the specialized activator cells disappear after transplantation before the curative effect is established. We therefore propose to test the feasibility and safety of inducing/enhancing the curative effects by administering the donor T cells together with recipient's specialized cells in a clinical phase I/II trial. If successful, results may provide a new treatment strategy for myeloma.