The antigen-specific immunosuppression induced by MDSCs helps to explain that T lymphocytes in lymphoid organs of tumor-bearing mice or blood of tumor patients can still respond to the stimuli of non-tumor-associated antigens, such as viruses, co-stimulatory molecules, IL-2, CD3−/CD28- specific antibodies [37, 40–42]. This evidence concerns the gene IL2 and neoplasm.