title: Macrophage--T-lymphocyte interaction in lichen planus. An electron microscopic and immunocytochemical study.
abstract: Papular lichen planus lesions from 12 patients were studied by a double-step immunocytochemical method to detect T-lymphocytes. Semithin sections were studied by light microscopy and ultrathin sections examined by electron microscopy. In the dermal infiltrate, many T-lymphocytes appeared closely juxtaposed to macrophages or Langerhans cells, frequently arranged in a rosette-like pattern. In the epidermis, T-lymphocytes were juxtaposed to macrophages or Langerhans cells and to degenerated keratinocytes. The close relationship between T-lymphocytes, macrophages or Langerhans cells and degenerated keratinocytes supports the hypothesis that lichen planus is immunological in nature: T-lymphocytes, after interacting with macrophages or Langerhans cells, become cytotoxic for keratinocytes.
mesh_terms: D006801:Humans; D007124:Immunoenzyme Techniques; D007801:Langerhans Cells / Q000276:immunology; D008010:Lichen Planus / Q000276:immunology* / Q000473:pathology; D008264:Macrophages / Q000276:immunology*; D008854:Microscopy, Electron; D012397:Rosette Formation; D012867:Skin / Q000276:immunology / Q000648:ultrastructure; D013601:T-Lymphocytes / Q000276:immunology*