Involvement of Indoleamine 2,3-Dioxygenase in Impairing Tumor-Infiltrating CD8⁺ T-Cell Functions in Esophageal Squamous Cell Carcinoma

Figure 1

Expression analysis of IDO protein in ESCC by immunohistochemistry and representative immunohistochemical staining for CD8⁺ TILs. (a, b) Example of IDO-low expression. (c, d) Example of IDO-high expression. (e, f) Staining of IDO in normal esophageal epithelial tissue, (e) absent; (f) weak. (g) Example of stromal CD8⁺ TIL staining in IDO-low expression tumor tissue. (h) Example of intraepithelial CD8⁺ TIL staining in IDO-low expression tumor tissue. (i) Example of stromal CD8⁺ TIL staining in IDO-high expression tumor tissue. (j) Example of intraepithelial CD8⁺ TIL staining in IDO-high expression tumor tissue (original magnification, (a) and (c) ×100; (b, d, e–j) ×200).

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