Whole thorax irradiation (WTI) induces time-dependent local changes in the T cell compartment of the lung tissue. C57BL/6 mice received 0 Gy or 15 Gy whole thorax irradiation. At specified time points cells were isolated from lung tissue and stained with antibodies against distinct leukocyte populations as indicated. (A) Gating strategy for lung cells: Living total lung cells were gated and further characterized by gating on CD45+ cells (leukocytes). All subpopulations were then gated on the CD45+ population. At different time points, cells were isolated from lung tissue, stained with antibodies against (B) total leukocytes (CD45+), (C) B-lymphocytes (B220+), (D) T-lymphocytes (CD3+), (E) CD4+ T-helper cells (CD4+) and (F) CD8+ T cells (CD8+) and analyzed by flow cytometry. Timelines of the indicated cell populations are shown with mean values ± SEM of percentages calculated on total lung cells (TLC). Cells of 6-9 mice per group were analyzed, ** p ≤ 0.01; *** p ≤ 0.001, two-way ANOVA followed by post-hoc Bonferroni test. (G) BALF (bronchoalveolar lavage fluid) was collected at 21 days post-irradiation from lungs of C57BL/6 mice irradiated with 15 Gy (right panel) and sham controls (left panel). Cytospin of BALF probes were stained with Giemsa and analyzed via bright-field microscopy: left panel: BALF from a sham control; right panel BALF from a lung irradiated with 15 Gy (40 × magnification). Pictures show one representative slide.