T regulatory cells and plasmocytoid dentritic cells in hansen disease: a new insight into pathogenesis?

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TitleT regulatory cells and plasmocytoid dentritic cells in hansen disease: a new insight into pathogenesis?
Publication TypeJournal Article
AuthorsMassone C, Nunzi E, Ribeiro-Rodrigues R, Talhari C, Talhari S, Schettini APM, Parente JNT, Brunasso AM, Puntoni M, Clapasson A, Noto S, Cerroni L
Abbrev. JournalAm J Dermatopathol
JournalThe American Journal of dermatopathology
Year of Publication2010
Publication Languageeng
KeywordsAdult, Aged, Biomarkers, Dendritic Cells, Female, Forkhead Transcription Factors, Humans, Immunoenzyme Techniques, Interleukin-3 Receptor alpha Subunit, Leprosy, Male, Middle Aged, Retrospective Studies, T-Lymphocytes, Regulatory, Young Adult

Leprosy is characterized by spectrum of histologically different granulomatous skin lesions that reflects the patient's immune response to Mycobacterium leprae. Presence, frequency, and distribution of both CD4+ CD25+ FoxP3+ T regulatory cells (T-regs) and CD123+ plasmacytoid dendritic cells in leprosy have never been investigated. We performed a retrospective immunohistochemical study on 20 cases of leprosy [tuberculoid tuberculoid (TT): 1 patient; borderline tuberculoid (BT): 3 patients; borderline lepromatous (BL): 5 patients; lepromatous lepromatous (LL): 5 patients; borderline borderline in reversal reaction (BB-RR): 1 patient; BT-RR: 2 patients; and erythema nodosum leprosum (ENL): 3 patients]. FoxP3-positive cells were present in 95% of the cases with an average density of 2.9% of the infiltrate. Their distribution was not related to granulomatous structures or special locations. There was no statistical difference of FoxP3 expression between TT, BT, BL, and LL, whereas a statistical significant increment (P = 0.042) was observed in patients affected by reversal leprosy reactions (BT-RR and BB-RR) compared with patients affected by ENL and patients with nonreactional disease forms (BL, LL, BT, TT). CD123 expression was not observed in any of the biopsy specimens evaluated; with the exception of 2 cases of ENL, in which a focal positivity for CD123 was observed. Our results show that plasmacytoid dendritic cells are not involved in the immune response against M. leprae while T-regs are present in leprosy skin lesions. These data raise the question if T-regs have a pathogenetic role in HD as previously demonstrated in Leishmania major and Mycobacterium tuberculosis.

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