Expression of γIFN by CD8⁺, CD14⁺, or CD68⁺ cells infiltrating KS lesions. Examples of double-staining by immunohistochemistry (APAAP/PAP) of γIFN and CD8, γIFN, and CD14 or CD68, γIFN, and FVIII-RA in a representative KS lesion. Similar results were obtained with other specimens. CD8⁺ cells (red stain) coexpressing γIFN (brown stain) had a mononuclear morphology (upper right panel), whereas anti-CD14 or anti-CD68 antibodies (red stain), recognizing monocytes-macrophages, costain γIFN⁺ (brown stain) spindle-shaped cells (lower left and right panels). In contrast, anti-γIFN antibodies (brown stain) do not stain FVIII-RA⁺ vessels (red stain, upper right panel), but γIFN⁺ cells are often localized in the proximity of vessels.