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.
Fraia Melchionda, Terry J. Fry, Matthew J. Milliron, Melissa A. McKirdy, Yutaka Tagaya, Crystal L. Mackall
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. We reserve the right to edit any letter for length, content, and clarity. Authors will be notified by e-mail if their letters were accepted. No appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at email@example.com.