In this DC vaccination trial we include relapsed MM patients, who are not responding to a first course of low dose DLI after an NMASCT from an HLA-matched unrelated donor (MUD). These patients receive a second course of low dose DLI in combination with DC vaccines generated from autologous monocytes. Objectives of the study are to evaluate the safety and efficacy of this novel therapy and the effect on the immune status of the recipient in correlation with toxicity and response. In future studies DLI-nonresponder recipients will be vaccinated with DCs loaded with hematopoietic mHags or with TAAs. This work is executed in collaboration with the Gene and Cell Therapy Facility, lead by Dr. I. Slaper-Cortenbach.