Adoptive transfer of CXCR6-deficient and WT P25-specific CD4+ T-lymphocytes showed an increase of CXCR6-deficient cells in the lungs and BAL at day 7 after PR8-P25 infection (Figure 6A), but by day 20 equivalent numbers of WT and CXCR6-deficient cells were present at all sites (Figure 6A). This evidence concerns the gene CD4 and infection.