Perils of immunohistochemistry: variability in staining specificity of commercially available COX-2 antibodies on human colon tissue.

We assessed the immunohistochemical (IHC) staining patterns of three commercially available COX-2 antibodies in human tissues. The location of positive stain in sequential serial 4-mu sections of formalin fixed, paraffin embedded tissue differed considerably. Staining patterns ranged from diffuse cytoplasmic to occasional perinuclear staining.