To characterize the immunophenotype of inflammatory cells in lichen sclerosus (LS), we performed a comparative case control study using one- and two-color immunohistochemistry and the nitro blue tetrazolium (NBT) reaction. Study material consisted of 100 biopsies from patients with LS or from 12 control groups consisting of inflammatory, scarring, and depigmenting cutaneous disorders. In addition, fresh tissue was sampled from four vulvectomy specimens for NBT testing. The typical inflammatory infiltrate of LS contained numerous epidermotropic CD3+, CD8+, CD57+ cells, increased intraepidermal HLA-DR+ cells, and a dermal infiltrate rich in CD8+, CD57+, HLA-DR+, and CD68+ inflammatory cells. Comparing LS to the 12 control groups, epidermotropic CD57+ lymphocytes independently predicted LS (P = 0.006, logistic regression, multivariate analysis). Among the 12 control groups, only specimens of the inflammatory stage of morphea exhibited numerous dermal CD57+ lymphocytes. Two-color immunohistochemistry confirmed the CD3+/CD8+CD57+ and CD3+/ CD8+/CD57+HLA-DR+ epidermotropic and dermal lymphocytic phenotypes and the dermal macrophage CD68+HLA-DR+ phenotype. In LS, the NBT reaction revealed evidence of superoxide production associated with CD68+HLA-DR+ cells. Expansion of CD8+CD57+lymphocytes is associated with viral infections, autoimmune disease, malignancies, and transplantation and is suspected to be the result of chronic excessive antigen challenge. In these pathologic states, CD8+CD57+ lymphocytes (as terminally differentiated, antigen-specific T cells) participate in the suppression of cytolytic activity to limit tissue damage. In LS, activated macrophages and lymphocytes indicate persistent antigen-driven inflammation. LS's numerous CD8+CD57+ lymphocytes may be either the mediators or the consequence of its hallmark sclerosis.
