Secondary expansion, long term maintenance, and qualitative changes of memory CD8+ and CD4+ T cells are not reliant upon T1IFN signaling.

<p>LCMV-immune UBC-Cre-ERT2+ and UBC-Cre-ERT2-IFNαβR^fl/fl mice were injected with tamoxifen and later rechallenged with LCMV. (A-C) CD8⁺ and (D) CD4⁺ T cells specific for the indicated LCMV immunodominant epitope were identified and quantified within the spleen at the indicated times post infection, using standard intracellular cytokine staining. Data are a summation of five independent experiments; each dot represents an individual mouse (at each time point, n = 4–11 per group). (E & F) The ability of CD8⁺ (E) and CD4⁺ (F) memory T cells to produce IFNγ, TNF, and IL-2 was examined using a standard ICCS assay at days 2, 5, 14, and 23 following secondary challenge. The loss of multifunctionality in memory cells soon after secondary infection, and its gradual restoration, are shown by the relative proportion, at each time point, of cells that are capable of producing one, two or three cytokines (black, grey and white segments, respectively).