tumor-infiltrating lymphocytes

tu·mor-in·fil·trat·ing lym·pho·cytes (TIL, TILS),

(lim'fō-sītz), lymphocytes collected from the site of a tumor and exposed to IL-2 in vitro to expand the population. When these cells are reinjected into the tumor-bearing host, they will specifically kill the tumor from which they originated.