IL-23 Maintains Tc17 CD8 T Cell Phenotype but not Commitment to IL-17 production (CCR6P.282)

CD8 T cells that produce IL-17 is an unknown field with lots to explore. In our previous studies, we found a novel subset of IL-17 producing CD8 T cells persisted longer in a self-antigen autoimmune model versus conventional IFN-g producing Tc1 cells; furthermore, Tc17 can convert to an IFN-g producing phenotype in vivo. In the present study, IL-17 producing Tc17 cells were purified by the cytokine-secretion assay and re-stimulated with anti-CD3/CD28 monoclonal antibodies with exogenous IL-12 or IL-23 cytokine. We found that IL-23 maintains IL-17-producing Tc17 CD8 T cell phenotype. However, administration of IL-23 is not enough to maintain the Tc17 phenotype. Addition of other cytokines such as IL-12 repressed IL-17 production and gene expression. In summary, IL-23 can maintain the Tc17 phenotype, but cannot promote the commitment of Tc17 CD8 T cells to an IL-17-secreting lineage.