In contrast to NK cells, CD8+ cytotoxic T cells are unable to recognize and kill tumor cells expressing Hsp70 on their plasma membrane, even after stimulation with the TKD peptide and IL-2 (31, 34), but come with a proven longevity after transfer into patients for long term effects such as chronic lymphocytic leukemia (CLL) (35). This evidence concerns the gene IL2 and B-cell chronic lymphocytic leukemia.