title: Increased Langerhans cell accumulation after mycobacterial stimuli.
abstract: OBJECTIVE
  To evaluate the role of Langerhans cells (LCs) in the local activation of leprosy lesions. LCs, acting as tolerance inducers and immune stimuli, are dendritic cells recently implicated in cutaneous homeostasis. The role of LCs in the defence against mycobacterial infection remains poorly understood.
  
  
  RESULTS
  The number and distribution of CD1a+ skin cells and HLA-DR and intercellular adhesion molecule (ICAM)-1 expression were analysed in leprosy skin lesions and in delayed-type hypersensitivity (DTH) tests. The results showed a high number of LCs in tuberculin and lepromin tests, in tuberculoid lesions and in the epidermis and dermis during type I and II reactions. In multibacillary lesions, however, the number of LCs was consistently low in comparison with other groups. Increased numbers of LCs were accompanied by marked HLA-DR and ICAM-1 expression, suggesting a strong relationship between these immunological events.
  
  
  CONCLUSIONS
  CD1a+ cells are implicated in the local immunological events taking place after mycobacterial stimuli and may account for the local activation of all types of reactional episodes in leprosy.
authors.affiliation: Leprosy Laboratory, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, and Department of Pathology and Laboratories, State University of Rio de Janeiro, RJ, Brazil.
authors.forename: A
authors.initials: A
authors.lastname: Miranda
authors.forename: T P
authors.initials: TP
authors.lastname: Amadeu
authors.forename: G
authors.initials: G
authors.lastname: Schueler
authors.forename: F B F
authors.initials: FB
authors.lastname: Alvarenga
authors.forename: N
authors.initials: N
authors.lastname: Duppré
authors.forename: H
authors.initials: H
authors.lastname: Ferreira
authors.forename: J A C
authors.initials: JA
authors.lastname: Nery
authors.forename: E N
authors.initials: EN
authors.lastname: Sarno
mesh_terms: D018949:Antigens, CD1 / Q000378:metabolism; D006684:HLA-DR Antigens / Q000378:metabolism; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007801:Langerhans Cells / Q000276:immunology* / Q000473:pathology; D015440:Leprosy, Lepromatous / Q000276:immunology* / Q000473:pathology; D009166:Mycobacterium leprae / Q000276:immunology / Q000472:pathogenicity; D012867:Skin / Q000276:immunology / Q000473:pathology
chemical_list: D018949:Antigens, CD1; C419393:CD1a antigen; D006684:HLA-DR Antigens; D018799:Intercellular Adhesion Molecule-1