CD4 and infection: In the rH4/Ad-H4 group two weeks after infection we observed that 14% of all CD8 T cells in the lungs were specific for TB10.4 and 2–3% for Ag85B, indicating that the CD8 epitopes were indeed processed and presented in the lungs at the very onset of infection, and that CD8 T cells primed by Ad5 vector delivery, as well as the CD4 T cells, were recruited to the site of infection (pre-infection the numbers in the lung were less than 0.1%, data not shown) (Fig. 5).