Fig. 4

GITR is required for the optimal formation of lung CD4 and CD8 Trm after influenza infection. a Schematic indicating that lethally irradiated CD45.1 hosts were reconstituted with a 1:1 mixture of GITR^−/− CD45.2: GITR^+/+ CD45.1 bone marrow cells. Chimeric mice were rested for 90 days and blood chimerism checked before i.n. infection with influenza A/HK-X31 and analyses were done at day 30 p.i. b Representative gating for donor CD69⁺ CD11a^hi CD4 Trm, polyclonal CD69⁺ CD103⁺ CD8 Trm, and tetramer⁺ CD8 Trm from the lung parenchyma. c Top: Representative flow cytometry plots showing proportions of GITR^+/+:GITR^−/− of CD4 T cells in blood before infection, of lung vascular (LV) CD4 T cell at day 30 p.i., and of lung tissue (LT) CD4 Trm at day 30 p.i. Bottom: Representative flow cytometry plots showing proportions of GITR^+/+:GITR^−/− of CD8 T cells before infection, of LV CD8 T cell day 30 p.i., and of LT D^b/PA_224–233-specific CD8 Trm day 30 p.i. d The normalized GITR^+/+:GITR^−/− ratio in the LV CD4 T cell and LT CD4 Trm compartments shown for individual mice. e The normalized GITR^+/+:GITR^−/− ratio in the LV CD8 T cell, LT polyclonal CD8 Trm, LT D^b/NP_366–374-specific CD8 Trm, and LT D^b/PA_224–233-specific CD8 Trm compartments is shown for each mouse. f The normalized GITR^+/+: GITR^−/− ratio in the CD44^hi CD62L⁺ CD4 Tcm and CD44^hi CD62L⁻ CD4 Tem compartments was evaluated in the spleen. g The normalized GITR^+/+:GITR^−/− ratio in the D^b/NP_366–374-specific CD8 T cell, D^b/PA_224–233-specific CD8 T cell, CD44^hi CD62L⁺ CD8 Tcm and CD44^hi CD62L⁻ CD8 Tem compartments was evaluated in the spleen. Normalization was done as described in Fig. 1. Each symbol represents an individual mouse, with bars indicating median with IQR. Statistical analyses performed using Wilcoxon test comparing pre- and post-infection ratios. Data were pooled from two independent experiments with 11 individual chimeric mice