Autologous stem cell transplantation (ASCT) is the standard of care consolidation therapy for eligible patients with myeloma but most patients eventually progress, an event associated with features of immune escape. Novel approaches to enhance anti-myeloma immunity after ASCT represents a major unmet need. Here, we demonstrate that patient mobilized stem cell grafts include high numbers of both effector CD8 T cells and immunosuppressive regulatory T cells (Treg). We show that BM residing T …