Aging Augments IL‐17 T‐Cell Alloimmune Responses

As increasing numbers of elderly patients require solid organ transplantation, the need to better understand how aging modifies alloimmune responses increases. Here, we examined whether aged mice exhibit augmented, donor‐specific memory responses prior to transplantation. We found that elevated donor‐specific IL‐17, but not IFN‐γ, responses were observed in aged mice compared to young mice prior to transplantation. Further characterization of the heightened IL‐17 alloimmune response with aging demonstrated that memory CD4+ T cells were required. Reduced IL‐2 alloimmune responses with age contributed to the elevated IL‐17 phenotype in vitro, and treatment with an anti‐IL‐17 antibody delayed the onset of acute allograft rejection. In conclusion, aging leads to augmented, donor‐specific IL‐17 immune responses that are important for the timing of acute allograft rejection in aged recipients. IL‐17 targeting therapies may be useful for averting transplant rejection responses in older transplant recipients. Aged mice exhibit elevated CD4+ memory alloimmune responses as compared to young mice, which contributes to the tempo of acute allograft rejection.