IL2 and neoplasm: They included: (A) allogeneic bone marrow transplantation for leukemia, largely successful via the “graft versus leukemia” effect [1]; (B) tumor reactive monoclonal antibodies (mAbs), effective in part via antibody dependent cell-mediated cytotoxicity (ADCC) [2]; (C) intravesical BCG for superficial bladder cancer, likely active via toll-like receptors on leukocytes [3]; and (D) administration of IL2 for melanoma and renal cell cancer [4].