title: T cell subsets and macrophages in lichen planus. In situ identification using monoclonal antibodies and histochemical techniques.
abstract: Skin lesions from 6 patients with lichen planus were studied for the presence of T cells and T cell subsets using monoclonal antibodies and indirect immunoperoxidase technique. Small numbers of Leu-2a-reactive suppressor-cytotoxic cells were present early in the basal cell layer in 2 patients with recent lesions. The analysis of T cell subsets revealed the predominance of anti-pan-T-cell (Leu-1)- and Leu-3a-reactive helper-inducer cells in 4 patients with older active lichen planus lesions. Significant numbers of suppressor-cytotoxic cells were observed in the papillary dermis and within the epidermis associated with hydropic degeneration of the basal cell layer. Activated T lymphocytes with focal acid phosphatase activity, together with activated histiocytes-macrophages with strong diffuse activity of acid phosphatase and non-specific esterase, were identified in the dermis and within the epidermis. These findings suggest that a cytotoxic immune process directed against the basal cell layer of the epidermis is the dominant pathogenic event in lichen planus.
mesh_terms: D000911:Antibodies, Monoclonal / Q000032:analysis*; D001706:Biopsy; D006801:Humans; D007124:Immunoenzyme Techniques; D007958:Leukocyte Count; D008010:Lichen Planus / Q000276:immunology* / Q000473:pathology; D008264:Macrophages / Q000276:immunology*; D012867:Skin / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal