Reporter-negative (IFNαβR-intact) CD8+ or CD4+ memory T cells do not preferentially expand during the recall response.

Abstract

<p>As described in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005861#ppat.1005861.g003" target="_blank">Fig 3A</a>, LCMV-immune Cre reporter (zsGreen) mice were generated, treated with tamoxifen, and subjected to secondary LCMV infection. Mice were sacrificed, and virus-specific CD8⁺ and CD4⁺ T cells were enumerated using intracellular cytokine staining, and evaluated for zsGreen expression, days 0, 2, 5 & 23 following the secondary infection. Representative epitope-specific responses in individual mice are shown. Cells were harvested at day 23 following secondary infection, and are gated on (A) CD8⁺ T cells or (B) CD4⁺ T cells. Numbers represent the proportion of the gated cells in each quadrant. (C-F) Cumulative data showing the proportion of zsGreen-positive cells at the indicated time points over the course of the recall response, in each of the four epitope-specific T cell populations. (G) At the indicated time points, splenocytes from Cre⁺ mice were exposed in vitro to IFNβ, and levels of pSTAT expression were evaluated. Representative plots are shown, gated on CD8 and zsGreen. The rightmost panel is a positive control, showing the responsiveness to IFNβ of day 23 post-secondary CD8⁺ T cells from Cre^- animals. Grey histograms = isotype control antibody.</p