title: Human antigen-specific regulatory T cells generated by T cell receptor gene transfer.
abstract: BACKGROUND
  Therapies directed at augmenting regulatory T cell (Treg) activities in vivo as a systemic treatment for autoimmune disorders and transplantation may be associated with significant off-target effects, including a generalized immunosuppression that may compromise beneficial immune responses to infections and cancer cells. Adoptive cellular therapies using purified expanded Tregs represents an attractive alternative to systemic treatments, with results from animal studies noting increased therapeutic potency of antigen-specific Tregs over polyclonal populations. However, current methodologies are limited in terms of the capacity to isolate and expand a sufficient quantity of endogenous antigen-specific Tregs for therapeutic intervention. Moreover, FOXP3+ Tregs fall largely within the CD4+ T cell subset and are thus routinely MHC class II-specific, whereas class I-specific Tregs may function optimally in vivo by facilitating direct tissue recognition.
  
  
  RESULTS
  To overcome these limitations, we have developed a novel means for generating large numbers of antigen-specific Tregs involving lentiviral T cell receptor (TCR) gene transfer into in vitro expanded polyclonal natural Treg populations. Tregs redirected with a high-avidity class I-specific TCR were capable of recognizing the melanoma antigen tyrosinase in the context of HLA-A*0201 and could be further enriched during the expansion process by antigen-specific reactivation with peptide loaded artificial antigen presenting cells. These in vitro expanded Tregs continued to express FOXP3 and functional TCRs, and maintained the capacity to suppress conventional T cell responses directed against tyrosinase, as well as bystander T cell responses. Using this methodology in a model tumor system, murine Tregs designed to express the tyrosinase TCR effectively blocked antigen-specific effector T cell (Teff) activity as determined by tumor cell growth and luciferase reporter-based imaging.
  
  
  CONCLUSIONS
  These results support the feasibility of class I-restricted TCR transfer as a promising strategy to redirect the functional properties of Tregs and provide for a more efficacious adoptive cell therapy.
authors.affiliation: Diabetes Center, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Brusko
authors.forename: Richard C
authors.initials: RC
authors.lastname: Koya
authors.forename: Shirley
authors.initials: S
authors.lastname: Zhu
authors.forename: Michael R
authors.initials: MR
authors.lastname: Lee
authors.forename: Amy L
authors.initials: AL
authors.lastname: Putnam
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: McClymont
authors.forename: Michael I
authors.initials: MI
authors.lastname: Nishimura
authors.forename: Shuhong
authors.initials: S
authors.lastname: Han
authors.forename: Lung-Ji
authors.initials: LJ
authors.lastname: Chang
authors.forename: Mark A
authors.initials: MA
authors.lastname: Atkinson
authors.forename: Antoni
authors.initials: A
authors.lastname: Ribas
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Bluestone
mesh_terms: D000328:Adult; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D055815:Young Adult
chemical_list: D011948:Receptors, Antigen, T-Cell