Development of a experimental model of infection using Leishmania braziliensis / Desenvolvimento de um modelo experimental para Leishmaniose Tegumentar Americana utilizando Leishmania braziliensis

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

American Tegumentary Leishmaniasis (ATL) is an endemic disease in Brazil. However, we still lack a reliable experimental model to study this disease. Our objective was to develop an infection model using L. braziliensis, the main etiological agent of ATL in our country, taking into account the parasite inoculum and route of infection. [MATERIALS AND METHODS] BALB/c mice were infected with 105 Leishmania braziliensis (MHOM/BR/01/BA788) into the ear dermis. The infection was followed for 10 weeks for the evaluation of lesion development and for evaluation of the immune response. [RESULTS] We observed that parasite expansion was accompanied by lesion development at the ear dermis. Lesions were similar to those observed in ATL patients (ie. nodular and ulcerated in the center). Lesions cured spontaneously and as seen by the presence of a scar. Histopathological analysis of infected ears showed the presence of, initially, a focal infiltrate consisting of mononuclear cells (lymphocytes and monocytes), neutrophils and few parasites. At the peak of lesion development, infected macrophages predominated. Thereafter, a weak infiltrate consisting of histiocytes, plasma cells, neutrophils and dermal fibrosis was observed with the absence of parasites. Regarding the draining lymph nodes, parasites could be detected throughout the infection period at a constant level. Results also show the up regulation in both monocyte/macrophage and granulocyte-recruiting chemokines.Measurement of intra cellular cytokine response by draining lymph nodes cells showed the up regulation of IFN-γ, IL-4, IL-5 and IL-10 by both CD4+ and CD8+ T cells. Later, cytokine expression decreased paralleled by lesion regression. [CONCLUSION] L. braziliensis inoculation in the ear dermis of mice results in a model of resistance to infection due to the development of a predominant Th1-type immune response. However, in this model, parasites are able to persist within draining lymph nodes of infected mice regardless of the development of a protective immune response

ASSUNTO(S)

balb/c leishmania braziliensis ifn- ifn-γ medicina american tegumentary leishmaniasis leishmaniose tegumentar americana balb/c leishmania braziliensis

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