CD62L-dependent lymph node trafficking is required for naïve CD8⁺ T cells to become activated following VacV skin infection, but not systemic LCMV infection.

(A) Equal numbers of WT (Thy1.1/1.2) and CD62L-/- (Thy1.1/1.1) naïve P14 CD8+ T cells were transferred into B6 mice and infected with either VacV-GP33 by skin scarification or LCMV by i.p injection. Frequencies of the transferred P14 CD8+ T cells was evaluated on the peak day of expansion (day 10 for VacV-GP33, day 7 for LCMV). (B) Quantification of (A). (C) WT or CD62L-/- naïve P14 CD8+ T cells were transferred into separate naïve B6 mice and infected with VacV-GP33 on the left ear skin. Expansion of the transferred T cells was then quantified. (D) Same as (C) except mice were infected with LCMV. (E, F) Quantification of circulating memory WT and CD62L-/- P14 CD8+ T cells on day 40 post-infection.