title: Primary human T lymphocytes engineered with a codon-optimized IL-15 gene resist cytokine withdrawal-induced apoptosis and persist long-term in the absence of exogenous cytokine.
abstract: IL-15 is a common gamma-chain cytokine that has been shown to be more active than IL-2 in several murine cancer immunotherapy models. Although T lymphocytes do not produce IL-15, murine lymphocytes carrying an IL-15 transgene demonstrated superior antitumor activity in the immunotherapy of B16 melanoma. Thus, we sought to investigate the biological impact of constitutive IL-15 expression by human lymphocytes. In this report we describe the generation of a retroviral vector encoding a codon-optimized IL-15 gene. Alternate codon usage significantly enhanced the translational efficiency of this tightly regulated gene in retroviral vector-transduced cells. Activated human CD4+ and CD8+ human lymphocytes expressed IL-15Ralpha and produced high levels of cytokine upon retroviral transduction with the IL-15 vector. IL-15-transduced lymphocytes remained viable for up to 180 days in the absence of exogenous cytokine. IL-15 vector-transduced T cells showed continued proliferation after cytokine withdrawal and resistance to apoptosis while retaining specific Ag recognition. In the setting of adoptive cell transfer, IL-15-transduced lymphocytes may prolong lymphocyte survival in vivo and could potentially enhance antitumor activity.
authors.affiliation: Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Cary
authors.initials: C
authors.lastname: Hsu
authors.forename: Marybeth S
authors.initials: MS
authors.lastname: Hughes
authors.forename: Zhili
authors.initials: Z
authors.lastname: Zheng
authors.forename: Regina B
authors.initials: RB
authors.lastname: Bray
authors.forename: Steven A
authors.initials: SA
authors.lastname: Rosenberg
authors.forename: Richard A
authors.initials: RA
authors.lastname: Morgan
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000276:immunology; D049109:Cell Proliferation; D003062:Codon / Q000235:genetics; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D005822:Genetic Vectors; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D019409:Interleukin-15 / Q000096:biosynthesis* / Q000235:genetics*; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D015202:Protein Engineering / Q000379:methods*; D012190:Retroviridae; D013601:T-Lymphocytes / Q000276:immunology*; D014161:Transduction, Genetic / Q000379:methods*
chemical_list: D003062:Codon; D016207:Cytokines; D019409:Interleukin-15; D007371:Interferon-gamma