IL-27 promotes splenic CD4⁺IL-10⁺ T cell development whereas ICOS is required for salivary gland CD4⁺IL-10⁺ T cell accumulation.

<p><i>Il-27r</i>α^-/- or WT (C57BL/6) mice were infected with MCMV and spleen and salivary gland CD4⁺/IL-10⁺ (A) responses were quantified and expressed at mean + SEM of 11 mice/group. (B) Representative bivariant FACS plots of IFNγ versus IL-10 expression by splenic CD4⁺CD3⁺ T cells. (C&D) gp130 and (E) ICOS expression by IL-10⁺ (Thy1.1⁺) and IL-10^- (Thy1.1^-) CD4⁺CD3⁺ T cells was assessed in 10-Bit mice and shown as representative FACS plots (C) and histogram overlays (E) with mean + SEM of 5–6 mice/group (D). Gating was determined using Thy1.1⁺ CD4⁺CD3⁺ cells derived from fluorescent minus one-stained samples from mice infected for 14 days. (F&G) WT (C57BL/6) mice were infected with MCMV and at d6 and d10 pi αICOS or Isotype antibody was added. At d14 pi (F) salivary glands and (G) spleen CD4⁺/IL-10⁺ responses were quantified and expressed as mean + SEM of 6 mice/group.