Transplant specific CD8⁺ T cells produced similar cytokine profiles but impaired activation in aged transplant recipients as compared to young recipients.

<p>A: Representative flow cytometric plots on day +7 post transplantation are shown along with isotype controls (IgG2b for IFNγ, IgG1 for IL-2 and TNFα). Young antigen specific CD8⁺ T cells produced similar amounts of TNFα, IL-2 and IFN-γ during <i>ex vivo</i> culture with OVA peptide regardless of the age of the recipient environment (cytokines were not produced if peptide was not added, data not shown). Proportions are shown in right upper quadrant. Note, that cytokines were not detected in either aged or young mice that were adoptively transferred but did not receive an OVA expressing skin transplant (data not shown). Similar results were noted at day +14 post transplantation (data not shown). Flow cytometric plots are gated on CD45.1⁺ cells. N = 3/group, representative data from three independent experiments with consistent results. B: Representative flow cytometric plots of adoptively transferred CD45.1⁺, OTI young T cells on day +7 post transplantation. Young antigen specific CD8⁺ T cells upregulated CD27 and downregulated CD62L to a greater degree in young transplant recipients compared to antigen specific CD8⁺ T cells in aged transplant recipients.