IL2 and neoplasm: Considering that renal cell carcinoma patients were often treated by immunotherapy, i.e., injections of IL-2 and IFN-α, the fact that tumor infiltration by T cells is of bad prognosis seems contra-intuitive, but considering that TIL numbers usually increase with the tumor grade, the simplest explanation for this correlation is that the grade of the tumors were not taken into account.