Figure 2. Cigarette smoke exposure promotes the expression of proinflammatory cytokines IFNγ and TNFα among CD8a⁺ T cells in the lung.

Balb/cJ mice were exposed for 6 months to FA or CS and CD8⁺ T cells were isolated from digested lungs by negative selection and stimulated with PMA and ionomycin in vitro with or without the presence of Brefeldin A so that cytokine expression could be measured by intracellular flow cytometry or ELISA. CD8⁺ T cells were pooled from N=6 mice/group and repeated in an independent experiment. A. Representative density plots indicate that chronic CS exposure results in an increase in the proportion of CD8a⁺ T cells that express TNFα alone or both TNFα and IFNγ compared to the CD8a⁺ T cells from FA exposed mice. B. Odds ratios comparing the proportion of CD8⁺ T cells that are TNFα⁺, TNFα⁺ IFNγ⁺, or TNFα⁺IFNγ⁻ between FA- and CS-exposed mice indicate that CS increases the likelihood that CD8⁺ T cells express TNFα and IFNγ. Error bars represent the 95% confidence intervals for the pooled odds ratios from two independent experiments. C. The geometric mean fluorescent intensity (gMFI) of TNFα staining is higher among CD8a⁺TNFα⁺ cells from CS-exposed mice compared to FA-exposed mice indicating higher production of TNFα. D. CD8⁺ T cells from CS-exposed mice stimulated in vitro in the absence of Brefeldin A produced more IFNγ as measured by ELISA.