Human cytotoxic T lymphocytes with reduced sensitivity to Fas-induced apoptosis

G Dotti, B Savoldo, M Pule, KC Straathof, E Biagi… - Blood, 2005 - ashpublications.org
G Dotti, B Savoldo, M Pule, KC Straathof, E Biagi, E Yvon, S Vigouroux, MK Brenner
Blood, 2005ashpublications.org
Effector-memory T cells expressing Fas (Apo-1/CD95) are switched to an apoptotic program
by cross-linking with Fas-ligand (FasL). Consequently, tumors that express FasL can induce
apoptosis of infiltrating Fas-positive T lymphocytes and subdue any antitumor host immune
response. Since Epstein-Barr virus (EBV)-associated tumors such as Hodgkin lymphoma
(HL) and nasopharyngeal carcinoma (NPC) express FasL, we determined whether EBV-
specific cytotoxic T lymphocytes (EBV-CTLs) could be modified to resist this evasion …
Abstract
Effector-memory T cells expressing Fas (Apo-1/CD95) are switched to an apoptotic program by cross-linking with Fas-ligand (FasL). Consequently, tumors that express FasL can induce apoptosis of infiltrating Fas-positive T lymphocytes and subdue any antitumor host immune response. Since Epstein-Barr virus (EBV)-associated tumors such as Hodgkin lymphoma (HL) and nasopharyngeal carcinoma (NPC) express FasL, we determined whether EBV-specific cytotoxic T lymphocytes (EBV-CTLs) could be modified to resist this evasion strategy. We show that long-term down-modulation of Fas can be achieved in EBV-CTLs by transduction with small interfering RNA (siRNA) encoded in a retrovirus. Modified T cells resisted Fas/FasL-mediated apoptosis compared with control cells and showed minimal cleavage of the caspase3 substrate poly(ADP-ribose) polymerase (PARP) protein after Fas engagement. Prolonged Fas stimulation selected a uniformly Faslow and FasL resistant population. Removal of responsiveness to this single death signal had no other discernible effects on EBV-CTLs. In particular, it did not lead to their autonomous growth since the modified EBV-CTLs remained polyclonal, and their survival and proliferation retained dependence on antigen-specific stimulation and on the presence of other physiologic growth signals. EBV-CTLs with knocked down Fas should have a selective functional and survival advantage over unmodified EBV-CTLs in the presence of tumors expressing FasL and may be of value for adoptive cellular therapy. (Blood. 2005;105:4677-4684)
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