By in vitro assays we explore the effects of these novel drugs on effector T cells, DC-mediated antigen presentation, NK cells and regulatory T cells. We also monitor the patients treated in three clinical studies (Named Patient Program, HOVON 76, DLI-Velcade study) to asses the in vivo effect of lenalidomide and bortezomib on T and B cell subsets and NK cells. Recently we have shown that lenalidomide alone or in combination with Dexamethasone is highly effective after SCT, and increases the absolute numbers of Foxp3+ regulatory T cells in the peripheral blood (Leukemia, 2008 ) This issue is now under further investigation by in vitro assays and by analysis of the patients enrolled in the HOVON 76 study.