Fig. 1

Memory CD4 T cells that demonstrate characteristics associated with tissue residence are present in the nose, and are enriched after intranasal exposure to pneumococcus. Nasal mucosa (NM) and spleen were harvested from mice 1–2 months after intranasal (I.N.) inoculation with serotype 6B pneumococcal strain 0603 or sham infection with PBS. Representative contour plots of “protected” CD4 T_m cells (CD44^HiCD62L⁻) are shown in (a) and quantitated in (b). c Representative contour plots of parenchymal CD4 T_m cells stained for CD69 and CD11a. Quantitation of frequency (d) and absolute number (e) of CD69⁺CD11a⁺CD4⁺ T_m cells. The results represent a pool of three experiments with 2–5 mice/group/experiment. Horizontal bars indicate the median value. *P < 0.05, ****P < 0.0001