01960nas a2200313   4500000000100000008004100001260001300042653001800055653002000073653001100093653003800104653002100142653002500163653002500188653000900213100001400222700001500236700001500251700002000266700001300286700001500299700001500314700001400329245007200343300001100415490000700426520119900433022001401632       2007                            d  c2007 Nov10aAntigens, CD110aHLA-DR Antigens10aHumans10aIntercellular Adhesion Molecule-110aLangerhans Cells10aLeprosy, lepromatous10aMycobacterium leprae10aSkin1 aMiranda A1 aAmadeu T P1 aSchueler G1 aAlvarenga F B F1 aDuppre N1 aFerreira H1 aNery J A C1 aSarno E N00aIncreased Langerhans cell accumulation after mycobacterial stimuli.  a649-560 v513 a<p><b>AIMS: </b>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.</p><p><b>METHODS AND RESULTS: </b>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.</p><p><b>CONCLUSIONS: </b>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.</p>  a0309-0167