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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 102, No. 5, 2007, pp. 625-630
Bioline Code: oc07098
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 102, No. 5, 2007, pp. 625-630

 en T-cell responses associated with resistance to Leishmania infection in individuals from endemic areas for Leishmania (Viannia) braziliensis   check for this species in other resources
Bittar, Rita C; Nogueira, Ricardo S; Vieira-Gonçalves, Ricardo; Pinho-Ribeiro, Vanessa; Mattos, Marise S; Oliveira-Neto, Manoel Paes; Coutinho, Sergio G & Da-Cruz, Alda M

Abstract

Subclinical or asymptomatic infection is documented in individuals living in endemic areas for leishmaniasis suggesting that the development of an appropriate immune response can control parasite replication and maintain tissue integrity. A low morbidity indicates that intrinsic factors could favor resistance to Leishmania infection. Herein, leishmanial T-cell responses induced in subjects with low susceptibility to leishmaniasis as asymptomatic subjects were compared to those observed in cured cutaneous leishmaniasis (CCL) patients, who controlled the disease after antimonial therapy. All of them have shown maintenance of specific long-term immune responses characterized by expansion of higher proportions of CD4+ as compared to CD8+ Leishmania reactive T-lymphocytes. Asymptomatic subjects had lower indexes of in vitro Leishmania induced lym-phoproliferative responses and interferon-gamma (IFN-γ) production in comparison to CCL patients. On the other hand, interleukin (IL-10) production was much higher in asymptomatics than in CCL, while no differences in IL-5 levels were found. In conclusion, long lived T-cell responses achieved by asymptomatic individuals differed from those who had developed symptomatic leishmaniasis in terms of intensity of lymphocyte activation (proliferation or IFN-γ) and regulatory mechanisms (IL-10). The absence of the disease in asymptomatics could be explained by their intrinsic ability to create a balance between immunoregulatory (IL-10) and effector cytokines (IFN-γ), leading to parasite destruction without producing skin tissue damage. The establishment of profiles of cell-mediated immune responses associated with resistance against Leishmania infection is likely to make new inroads into understanding the long-lived immune protection against the disease.

Keywords
Aedes aegypti - Aedes albopictus - dengue - Manaus

 
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