Figure 6. Decreases in the NP-specific CD8⁺ T cell response in the lungs of coinfected animals on day 8 post influenza infection correlates with increased cell death.

Cells were isolated from the lung and MLN of animals infected with influenza virus or coinfected. Following staining for CD8 and tetramer, 7-AAD was added to identify cells that had lost membrane integrity as an indicator of cell death. A. Representative flow plots. Cells were pre-gated on CD8 and tetramer. B. Averaged data from 2–3 independent experiments assessing a total of 21–22 (d8) or 8–11 (d11) mice/infection condition. C. Cells were isolated from the lung and MLN of animals infected with influenza virus alone or coinfected. Following staining for CD8 and tetramer, cells were fixed, permeabilized and stained with antibodies specific for active caspase-3. The percentage of CD8⁺tetramer⁺ cells that stained positive for active caspase 3 is shown. Data are the average from 4–6 mice/condition. A two tailed student’s t test was used to determine significance. ** p<0.01, **** p<0.0001