Large scale expansion of human tumor infiltrating lymphocytes with surface-modified stimulator cells for adoptive immunotherapy

Expansion of tumor infiltrating lymphocytes (TIL) in vitro is hampered by several factors, including a limited amount of lymphocytes obtained from different tumors, unknown target antigens and limited supply of antigen-presenting cells (APC) which are generally believed to be essential in the classical way of T cell stimulation and expansion. In approaching these difficulties, we have recently used surface-oxidized allogeneic PBL to stimulate the TIL periodically in the presence of a low dose of rIL-2 (200 IU/ml). TIL derived from 22 (out of 23) tumor specimens could be expanded with 20 -10(7) fold increases over 6-16 weeks to a sufficient amount of 10(9) -10(11) cells for adoptive immunotherapy. In contrast, only 2-100 fold increase were observed in six tumor specimens (out of 23) when 200 IU/ml rIL-2 was used only. The phenotypes, autologous tumor reactivity and cytolytic capability of TIL propagated with surface-oxidized stimulators were similar to those expanded in the presence of IL-2 alone. These data suggest that expanding TIL with surface-modified stimulator cells could be a useful alternative method to obtain a large amount of tumor specific cytolytic T cells for clinical immunotherapeutic use, irrespective of tumor-antigen stimulation and MHC restriction.