CD200 and neoplasm: The immunosuppressive mechanism promoted by CD200:CD200R interaction relies, as mentioned above, on the inhibition of macrophages, induction of regulatory T cells, switching of cytokine profiles from Th1 to Th2, inhibition of tumor-specific T cell immunity and induction of MDSC (myeloid-derived suppressor cells) expansion [77,78,96,98,99].