Resumo

VAQUERO, N. L; MUSSARI, C  e  GIRARD BOSCH, M. C. Th1-TH2 balance. Natural model: Hansen'disease. Rev. argent. dermatol. [online]. 2010, vol.91, n.3, pp.00-00. ISSN 1851-300X.

Hansen' disease, caused by Mycobacterium leprae, is an infectious illness whose wide clinical and immunopathologic spectrum correl with different Th1/Th2 responses patterns. The prefferencial activation of the CD4 T cells subset play an important rol in it's pathogenia and  provides a natural model of that balance. Either polars forms present a defwed citokynes secretion profile: Th1 cells (IL-2 and IFN-g) dominate in tuberculoid form, whereas cytokines typically produced by Th2 cells (IL-4, IL-5 and IL-10) dominate in lepromatous form. In the first case, the macrophagic activation kills M leprae. It's lesions are located in nerves and skin only. In the second case, cell-mediated immunity is absent. The bacilli multiply uncontrolably in macrophages and infection is widely disseminated affecting other organs. Humoral immunity is exacerbated and have  high  levels of  antibodies that cannot reach intracellular germ. The factors that determine whether the proliferation CD 4 T cells differentiate into Th1 or Th2 cell are not fully understood.  Several hypothesis include genetics factors, prevail of cytokinesin the microenviroment, macrophagic disfunction; alterations in the coestimulatory molecules, on toll receptors of the innate immunity, etc. In recent years times new limphocytes  subsets have been discovery (CD4+CD 25+, Tr1, Th3, Th17) that could be implicated in this desregulated immune reponses.

Palavras-chave : Leprosy; Hansen'disease; Immunopathology; T helper 1-T helper 2 limphocytes subsets (Th1/Th2).