Expression of γIFN, CD8, CD14, and CD68 in a representative KS lesion (lower panels, original magnification × 400) and uninvolved tissue (upper panels, original magnification × 1,000) by immunohistochemistry (APAAP) as described in Materials and Methods. Positivity for γIFN (red stain) was mostly observed in mononuclear cells, but also in spindle-shaped cells, as compared with uninvolved tissues. A strong increase in CD8⁺ and CD14⁺/CD68⁺ infiltrating cells, often with a subendothelial localization, was also observed in KS lesions, whereas these infiltrating cells are rare in uninvolved tissues. Similar results were obtained in all KS lesions analyzed, but were prevalent in early stage lesions.