Expression of CD25 and IDO in peritumoral dendritic cells. Example of a gastric carcinoma with considerable inflammatory reaction. Photographs were taken by a JVC digital camera connected to a Zeiss Axiophot microscope. (A) Overview of a sample slide with invasive tumor cell populations and peritumoral inflammatory reaction (magnification, × 100; hematoxylin-eosin staining). (B) Magnification of the border area of the carcinoma: double-immunostaining for S100 (red) and IDO (blue) demonstrates a distinct population of purple-colored double-stained cells (#); magnification, × 1000. (C) Tumor-draining lymph node next to the carcinoma: double immunostaining for S100 (red) and IDO (blue). S100 single-positive DCs (red) as well as S100/IDO-coexpressing cells (purple colored, #) are seen; magnification × 1000. (D) Peritumoral CD25⁺ cells (red) are more numerous than S100⁺ DCs (blue). Few double-stained purple cells are visible (#); magnification, × 250. (E) Intratumoral S100⁺ DCs in close proximity to double-stained S100⁺ CD25⁺ DCs (purple colored, #); magnification, × 400. For panel A, a 10 ×/0.32 Plan Apochromat objective lens was used to visualize the image; for panels B-E, a 63 ×/1.40 oil-immersion Plan Apochromat objective lens was used to visualize images.