To further understand the biological consequences of TSLP on memory cells, we next co-transferred equal numbers of congenically marked WT and Crlf2-/- memory P14 cells (>30 days after influenza infection) into naïve WT mice and infected these mice with PR8-33 intranasally the following day (schematic in Figure 4A, left; CD44 expression on WT and Crlf2-/- memory P14 cells and ratio of transferred cells Figure 4A, right panels). This evidence concerns the gene CD44 and influenza.