Figure 2.

An increased frequency of regulatory T cells (Tregs) at steady-state predicts protection from death after subsequent virus infections. Age-matched male or female CC-RIX were infected with H1N1 influenza, severe acute respiratory syndrome-coronavirus, or West Nile virus and monitored for survival. Based on these data, they were grouped into “No Mortality” or “Mortality in all 3” categories as shown in Table 1. A second cohort of 3–6 age-matched male mice of the same CC-RIX were euthanized, and splenic cells were analyzed by flow cytometry staining to determine the frequency of Foxp3⁺ Tregs (A), CD44⁺ Tregs (B), glucocorticoid-induced tumor necrosis factor receptor (GITR)⁺ Tregs (C), and CD25⁺ Tregs (D). Statistical significance was determined by Mann-Whitney test.