Fig. 2

Breast cancer samples of high collagen density have fewer infiltrating T cells. a-d Histological sections of triple-negative breast cancers were picrosirius red (PSR)-stained for visualization of fibrillar collagen (a and c, red color) or immunostained for CD8 for visualization of cytotoxic T cells (B and D, brown color). a-b Example of a specimen containing low levels of collagen (a) and high abundance of tumor-infiltrating T cells (b). c-d Example of a specimen containing high levels of collagen (c) and low abundance of tumor-infiltrating T cells (d). Size bar: (a and c) 1 mm; (b and d) 100 μm. e Using Visiopharm-assisted automated image analysis, 20 triple-negative breast cancer sections were analyzed for the PSR-positive area and the number of tumor-infiltrating CD8+ T cells. Each dot in the graph represents an individual cancer sample. Pearson correlation r = 0.37, P = 0.11. f Areas of high and low collagen density were defined and the number of CD8+ T cells in these areas was assessed