Cox-2 expression is enhanced in lesional psoriatic skin. Cox-2 expression (red) was detected by immunohistochemistry in (A) healthy skin and (C-D) in psoriatic skin. Nuclei were stained by hematoxylin (blue). (B) An isotype control antibody in lesional psoriatic skin served as negative control. (E) For quantification of Cox-2 expression, morphometric image analysis was performed by scanning 5 images per sections. The sum of pixels was evaluated, and the mean plus or minus SD of the number of pixels from 6 different psoriatic skin samples and 6 healthy skin samples is shown. (F-G) In lesional psoriatic skin, fibroblasts were detected by an anti–Thy-1 antibody (blue-gray) and Cox-2 expression by the anti–Cox-2 antibody (red). Arrows indicate Thy-1/Cox-2 double-positive cells.