FIGURE 7.

Down-regulation of cytokine receptors and diminished homeostatic proliferation by splenic memory 2C cells in the airways. A, Aliquots of sorted CD8⁺ cells (5 × 10⁶) from pooled spleens of infected recipient mice 30 dpi were transferred intratracheally into naive B6 mice. Bronchial lavage was collected 7 and 14 days after transfer and cells were assayed for IL-7Rα, IL-15Rβ, γ_c, and 2C TCR expression. Data shown are gated on 2C cells (2C TCR⁺ CD8⁺). Solid line, splenic memory 2C cells in the airways; shaded area, naive 2C cells. Numbers shown are relative percentages of the MFI of recovered memory 2C cells normalized to the MFI of naive 2C cells. B, Purified CD8⁺ cells (5 × 10⁶) from pooled spleens of infected recipient mice 30 dpi were labeled with CFSE and transferred either intratracheally or i.v. into naive B6 mice. Fourteen days later cells were collected from spleens of recipients transferred i.v. and from airways of recipients transferred intratracheally, and analyzed for 2C TCR, CD8, and CFSE. 2C TCR vs CFSE profiles are shown for gated CD8⁺ cells (bottom two panels), and the CFSE profiles of 2C TCR⁺ CD8⁺ cells are shown by histograms.