Differential staining of cytoid bodies and skin-limited amyloids with monoclonal anti-keratin antibodies.

The authors have used 5 different monoclonal antikeratin antibodies to study the antigenic profiles of cytoid bodies and skin-limited amyloids. Monoclonal antibodies AE1 (which stains the basal cell layer in normal human epidermis), AE2 (suprabasal layers), AE3 (whole epidermis), EKH4 (lower 2-3 layers), and EKH1 (recognizes all classes of intermediate filaments) were used to stain frozen skin sections by the indirect immunofluorescent or indirect immunoperoxidase technique. Cytoid bodies in lichen planus (LP) and discoid lupus erythematosus (DLE) were strongly stained with AE1, AE3, EKH4, and EKH1 antibodies but were negative with AE2. In contrast, amyloids in lichen amyloidosus and macular amyloidosis were stained strongly with EKH4 but only weakly or not at all with AE1, AE2, AE3, and EKH1. Amyloid associated with epithelial tumors showed closer immunologic profiles to cytoid body. These findings suggest that epidermal keratins are the major precursor substance of skin-limited amyloids as well as cytoid bodies in LP and DLE. Sequential changes in antigenic profiles from basal cells to amyloids through cytoid bodies further suggest that cytoid bodies may represent one of the precursor substances of skin-limited amyloids.