Type I IFN-mediated induction of Blimp-1 in CD4 T cells can occur independently of IL-2 signaling.

<p>(<b>A-B</b>) Blimp-1 reporter mice were administered either MOPC or α-IFNAR antibodies and were infected with either10⁶ pRBCs. (<b>A</b>) Representative flow plots depicting the expression of CD25 on <i>Plasmodium</i> infection-induced effector CD4 T cells from MOPC and α-IFNAR-treated mice on day 8 p.i. (<b>B</b>) Cumulative data showing surface CD25 expression (gMFI) on <i>Plasmodium</i> infection-induced splenic CD44^hiCD11a^hi CD4⁺ T cells. Data (Mean +/- SEM) in (<b>B</b>) are pooled from 2 independent experiments (3–4 mice/group). (<b>C</b>) Summary data (Mean +/- SD) showing CD25 expression (gMFI) on WT and <i>ifnar1</i>^-/- CD4 T cells recovered from <i>tcrα</i>^-/- on day 4 post-<i>Plasmodium</i> infection. Data in (B,C) were analyzed using Mann-Whitney non-parametric tests of statistical significance. (<b>D,E</b>) Naïve CD4 T cells from Blimp-1-eYFP reporter mice were stimulated with α-CD3/α-CD28 and treated with or without rIFNβ or anti-IL-2 blocking antibodies. (<b>D</b>) Summary data (Mean +/- SD) depicting surface expression of PI3K-dependent CD98 on CD44^hi CD4⁺ T cells cultured under the various treatment conditions. (<b>E</b>) Summary data (Mean +/- SEM) showing Blimp-1-eYFP expression (gMFI) in CD44^hi CD4⁺ T cells under the various treatment conditions. Data in (<b>E</b>) are normalized to Blimp-1 expression (MFI) in non-stimulated CD4 T cells and are pooled from 3 independent experiments. Data in (D,E) are representative of 3 independent experiments and were analyzed using Kruskal-Wallis non-parametric tests of statistical significance. <i>N</i>.<i>S</i>. = not statistically significant. *P<0.05, **P<0.01.