To assess whether adult NP-specific CD8+ T cells could be activated by pup lung cells, cells from the naïve pup or adult lung digest were co-cultured with CD8+ T cells isolated from the spleens of PR8-infected adult mice at day 10 post-infection and IFNγ production was measured at day 3 of culture by ELISA (Figure 4H). Here, CD8A is linked to infection.