title: Induction of cutaneous delayed hypersensitivity reactions in mice sensitized with intragastrically administered hapten: activation of Langerhans cells in the sensitization and elicitation phases.
abstract: BACKGROUND
  As seen in atopic dermatitis, allergic diseases often produce lesions both in the gastrointestinal tract and the skin, suggesting the involvement of an immunological relationship between the two organs in the pathogenesis.
  
  
  OBJECTIVE
  To study the role of gastric and epidermal Langerhans cells (LCs) in the sensitization and elicitation phases, respectively, of cutaneous delayed-type hypersensitivity (DTH) reactions to intragastrically administered hapten.
  
  
  METHODS
  BALB/c mice, which were subjected to intragastric administration of trinitrochlorobenzene 5 days previously, received an elicitative challenge of the same hapten to the ear skin. Sections of the ear were immunostained for CD4 and CD8. Epidermal sheets of the ear and epithelial sheets of the forestomach were immunostained for I-A and observed under a confocal laser scanning microscope.
  
  
  RESULTS
  Cutaneous DTH reactions were induced in mice, as demonstrated by an increase in ear thickness and a prominent infiltration of CD4+ and CD8+ lymphocytes at 24-36 h after the elicitative challenge. In the elicitation phase, epidermal LCs showed a significant increase in size, indicating in vivo activation, at 24 h. In the sensitization phase, gastric LCs increased in size at 2 h, became round at 6 h, and decreased in number at 24 h, possibly representing the sequential events of LC activation and migration from the epithelium.
  
  
  CONCLUSIONS
  The present study demonstrated that gastric LCs and epidermal LCs were activated in vivo in the sensitization and elicitation phases, respectively, of cutaneous DTH reactions in orally sensitized mice.
mesh_terms: D000818:Animals; D005260:Female; D006241:Haptens / Q000009:adverse effects*; D006968:Hypersensitivity, Delayed / Q000139:chemically induced* / Q000276:immunology; D007114:Immunization; D007801:Langerhans Cells / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D012867:Skin / Q000276:immunology; D013270:Stomach / Q000276:immunology
chemical_list: D006241:Haptens