CD27 is an immunostimulatory IC and a member of the TNFR (tumor necrosis factor receptor) superfamily. In humans, CD27 is constitutively expressed on most T cells, memory B cells, plasma cells, and Natural Killer cells. Expression of CD70 is tightly controlled and induced transiently in antigen-presenting cells following stimuli exposure, such as TFN-α, irradiation, or TLR agonists [1, 2]. The CD27–CD70 axis plays an important role in immune regulation. In concert with the T cell receptor (TCR) crosslinking, it contributes to efficient T cell activation, proliferation, survival, maturation of effector capacity, and T cell memory [1, 2].