IL2 and neoplasm: The manufacture of TIL for therapeutic use occurs in a multistep process involving surgical resection of tumor, extraction of TIL from tumor fragments in the presence of IL-2 in a step known as “pre-REP” (with REP indicating rapid expansion phase), followed by expansion of TIL in the presence of IL-2, irradiated PBMC feeders, and agonistic anti-CD3 OKT3 antibody in the REP (29–32).