Rapamycin decreases expression of IFN-γ in old CD4+ T cells following skin transplantation. Skin graft recipients were treated daily with either PBS or Rapamycin. By day 7, splenic frequencies of CD4+IFN-γ+ T cells were assessed by flow cytometry using isotype controls. Representative plots are given for each group. Furthermore, cell culture supernatants after restimulation of recipient splenocytes with donor-type splenocytes for 72 hrs were analyzed for IFN-γ by ELISA. (n=5-6 animals/group; data represent mean ± SD; *, p<0.05; **, p<0.01; ***, p<0.001)