Figure 6.

Transmembrane fractalkine is expressed by cytokeratin-positive cells with the human tonsil. Human tonsils were collected after routine tonsillectomy. Frozen sections (8 to 10 μm) were cut for immunohistochemical analysis. Adjacent serial sections were stained using the rabbit α-C-pep (A, brown) or mouse α-cytokeratin AE1/AE3 (B, blue). Another section ∼30 μmol/L further into the sample was double-labeled using both reagents (C). The rabbit α-C-pep reagent strongly detects a subpopulation of cells within the epithelial crypts. Staining for the cytokeratins AE1 and AE3 revealed staining restricted to the epithelial crypts with strong staining on cells with a similar distribution and morphology to A, with widespread but more diffuse staining throughout the crypts. Double labeling with rabbit α-C-pep (brown) and α-cytokeratin (blue) show clear double labeling (purple) of discrete cells within the crypts and especially along the internal border of the crypts. Original magnifications, ×400.