FIG. 3.

CD4⁺ T cells home to the lung airways upon virus challenge of perforin KO and wild type animals. Perforin-KO and B6 mice were vaccinated with DNA (D) and vaccinia virus (V) in a prime-boost regimen. Inoculations were in the order D-D-V. One month after the last injection, vaccinated and unvaccinated mice were challenged with rSeV-env (1 × 10⁵ PFU/animal). Mice were given ip injections with the anti-CD8 2.43.1 mAb on days −5, −3, −1, +1, and +3 relative to rSeV-env challenge. BAL lymphocytes from individual vaccinated and unvaccinated animals were counted 5 days after challenge. The fraction of CD4⁺ T cells among BAL lymphocytes was determined by flow cytometry (samples were combined from each test group to ensure sufficient numbers for the CD4⁺ T cell analysis). Total lymphocyte numbers were multiplied by the CD4⁺ T cell fraction to determine the approximate CD4⁺ T cell count in the BAL of each animal.