title: Adjuvant IL-7 or IL-15 overcomes immunodominance and improves survival of the CD8+ memory cell pool.
abstract: Current models of T cell memory implicate a critical role for IL-7 in the effector-to-memory transition, raising the possibility that IL-7 therapy might enhance vaccine responses. IL-7 has not been studied, to our knowledge, before now for adjuvant activity. We administered recombinant human IL-7 (rhIL-7) to mice during immunization against the male antigen HY and compared these results with those obtained from mice immunized with rhIL-2 and rhIL-15. Administration of rhIL-7 or rhIL-15, but not rhIL-2, increased effector cells directed against these dominant antigens and dramatically enhanced CD8(+) effectors to subdominant antigens. The mechanisms by which the cytokines augmented effector pool generation were multifactorial and included rhIL-7-mediated costimulation and rhIL-15-mediated augmentation of the proliferative burst. The contraction phase of the antigen-specific response was exaggerated in cytokine-treated mice; however, CD8(+) memory pools in rhIL-7- or rhIL-15-treated groups demonstrated superior long-term survival resulting in quantitative advantages that remained long after the cytokines were discontinued, as demonstrated by improved survival after challenge with an HY-expressing tumor undertaken several weeks after cytokine cessation. These results confirm the adjuvant activity of rhIL-15 and demonstrate that rhIL-7 also serves as a potent vaccine adjuvant that broadens immunity by augmenting responses to subdominant antigens and improving the survival of the CD8(+) T cell memory pool.
authors.affiliation: Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA.
authors.forename: Fraia
authors.initials: F
authors.lastname: Melchionda
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Fry
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Milliron
authors.forename: Melissa A
authors.initials: MA
authors.lastname: McKirdy
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tagaya
authors.forename: Crystal L
authors.initials: CL
authors.lastname: Mackall
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D006182:H-Y Antigen / Q000276:immunology; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology*; D007156:Immunologic Memory / Q000187:drug effects* / Q000276:immunology; D019409:Interleukin-15 / Q000494:pharmacology*; D015851:Interleukin-7 / Q000494:pharmacology*; D051379:Mice; D011994:Recombinant Proteins / Q000494:pharmacology; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology; D013997:Time Factors
chemical_list: D000276:Adjuvants, Immunologic; D006182:H-Y Antigen; D016056:Immunodominant Epitopes; D019409:Interleukin-15; D015851:Interleukin-7; D011994:Recombinant Proteins