A comparative immunohistochemical study of lichen planus and discoid lupus erythematosus

A comparative immunohistochemical study was performed on skin biopsies from 10 patients with lichen planus and 10 patients with discoid lupus erythematosus (DLE). A panel of antibodies against T lymphocytes (UCHL-1, OPD-4, CD8, CD45), B lymphocytes (L-26), granulocytes (Leu-M1), activation markers (Ki-1, LN-3), macrophages, fibroblasts and dendritic cells (FXIIIa, S-100, Mac-387, K.P-1, vimentin), endothelial cells (CD34), and epithelial cells (epithelial membrane antigen) was employed using a peroxidase-anti-peroxidase technique. The recently released CD8 antiserum required microwave antigen retrieval of formalin-fixed, paraffin-embedded tissue to label lymphocytes. The results showed many similarities in the lymphocyte subsets and macrophages between lichen planus and discoid lupus erythematosus. The most important differences between the two conditions were statistically significant increases in the number of S-100⁺ cells in the epidermis and dermis, FXIIIa⁺ cells in the dermis and CD34⁺ vessels within the inflammatory infiltrate in lichen planus.