The earliest trials of ACT using lymphocytes isolated from cancer samples (also known as tumor-infiltrating lymphocytes, or TILS) were conducted at the surgical branch of the National Cancer Institute (NCI) in Bethesda, Maryland, USA in 1988,21 following the demonstration in 1987 that TILs could be cultured with the aid of the lymphotrophic cytokine IL-2 and exhibited cytotoxic activity against cancer cells in vitro. Here, IL2 is linked to cancer.