Fig 1: Increased interactions between CD8+ T cells, CD45+ FSP1+ cells in distal airways of chronic obstructive pulmonary disease (COPD) patients.(A, B) Representative stainings of CD8 (brown, A), CD45 (red, B), and FSP1 (green, B) in distal bronchial tissue specimens from a control subject (left) and a COPD patient (right). The yellow arrowheads indicate fibrocytes, defined as CD45+ FSP1+ cells. (C) Quantification of CD8+ T cells and fibrocyte densities (normalized by the sub-epithelial area) in one specimen/patient (n=20 control subjects, n=12 patients with COPD). (D) Merged segmented images for CD8 and CD45-FSP1 staining, showing CD8+ T cells and CD45+ FSP1+ cells, respectively, in magenta and yellow. The white arrows indicate interacting cells, detected by dilatation of CD8 positive particles. (E) Table showing the correspondence between dilatations in pixels and µm. (F) Quantification of interacting cell densities (normalized by the sub-epithelial area) in one specimen/patient, using the different dilatations sizes (E). (G) Distance maps built from the binary image produced from CD8 staining, with FSP1+ CD45+ cells (blue outlines). (H) Quantification of the mean minimal distances between fibrocyte and CD8+ T cells in one specimen/patient. (I) Cluster analysis performed by Delaunay triangulation on segmented images for CD8 and CD45-FSP1 staining, followed by the application of a threshold value (40 µm) above which connections are not kept. CD8+ T cells and fibrocytes appear, respectively, with green and red dots, connections are shown in blue. (J) First row: densities of clusters containing exclusively CD8+ T cells (‘CD8 clusters’), fibrocytes (‘Fib clusters’), and both cell types (‘CD8-Fib clusters’) normalized by the sub-epithelial area in one specimen/patient. Second row: mean number of cells by cluster. (C, F, H, J) The medians are represented as horizontal lines, n=20 specimens from control subjects, n=12 specimens from patients with COPD. *p<0.05, **p<0.01; ***p<0.001. unpaired t-tests or Mann-Whitney tests.