PDCD1 and plasma cell myeloma: DCs combined with lenalidomide and PD-1 blockade also heightened the anti-myeloma cell mediate immunity by inducing the Th1 polarization, as evidenced by the high-level production of IFN-γ, and by suppressing Th2 immune responses, as evidenced by the low-level production of IL-10 and TGF-β.