Immunohistochemical expression of ARG2 in stromal cells within and around necrotic areas in PDC tissue.

<p>(A) Histology of PDC tissue in low- (upper columns) and high-power view (lower columns). HE staining (left columns) and immunohistochemistry for ARG2 (center columns) and cytokeratins (right columns) in serial tissue sections. Necrotic areas are surrounded by star marks (large area of necrosis is located at bottom right) in the upper HE photo and the rectangle (light blue) corresponds to the area of the lower column. (B) Immunohistochemistry for ARG2 (left upper column) and for mitochondria (left lower column) in high-power views. Positive staining of ARG2 is visualized as a dot-like or coarse granular pattern in the cytoplasm of spindle cells. This positive staining pattern was compatible with mitochondrial antigen. Double immunofluorescence (right column) shows ARG2 (green), mitochondria (red), and nuclei (white). Almost all ARG2-positive staining is co-localized with mitochondria (yellow). (C) Immunohistochemical expression of ARG1 was observed only in neutrophils. Upper and lower columns are middle- and high-power views, respectively.