Figure 7. LIGHT controls memory and recall responses to influenza virus infection.

(A) Equal numbers (5 × 10⁴) of WT and LIGHT^−/− naïve (CD44^lo) OT-I (Vα2⁺Vβ5⁺) transgenic CD8 T cells were adoptively transferred into WT mice and infected with PR8-SIINFEKL (i.n) the following day. Lungs were harvested at day 40 post-infection and stained for CD8, CD44, Vα2, Vβ5 and NP-tetramer (top and bottom). OT-I cells from lungs of recipients were re-stimulated in vitro with OVA peptide and stained intra-cellularly with IFN-γ (middle). (B & C) WT & LIGHT^−/− CD8 T cell recipient mice that were previously infected with rVacV-WR-OVA (i.n) were re-infected with PR8-SIINFEKL (i.n) after 40 days from primary infection. Lungs were harvested at day 6 and stained for CD8, CD44, Vα2, Vβ5 and NP-tetramer. (D) Numbers and fold change in the cell numbers between WT CD8 T cells and LIGHT^−/− CD8 T cells from day 40 post-primary infection to day 6 post re-infection was quantified. *, P<0.05. Similar results were obtained in two independent experiments and results are the mean ± SEM (n = 3 mice/group).