Fig. 7: Caspase-3 is active in vivo in proliferating T cells after influenza infection

Mice received influenza virus strain A/Puerto Rico/8/1934 H1N1 virus (FLU) or PBS control intranasally and lymph nodes were extracted 6 days after infection. Mediastinal lymph node cells (flu-infected mice) or non-mediastinal lymph node cells (PBS control mice) were stained and analyzed by flow cytometry. a Representative contour plots of live CD4⁺ (left) or CD8⁺ (right) T cells from PBS control mice (top) or flu-infected mice (bottom) for CD44 vs. active caspase-3. The two rectangular inserts identify the CD44^high (upper) and CD44^low (lower) populations. All events to the right of the vertical line are positive for active caspase-3. Numbers represent the percentage of CD44^high or CD44^low gated cells that are positive for active caspase-3 (% + ), and the median fluorescent intensity of active caspase-3 (MFI). b Graphs of the percent positive cells for active caspase-3 (top) and MFI (bottom; two-way ANOVA with Tukey’s correction; mean ± S.D.; *p < 0.001, **p < 0.0001. NS not significant. n = 5 mice per group)