Received: September 1, 2008.

Accepted: February 13, 2009.

Abstract published online: March 5, 2009.

Full paper published online: August 31, 2009.

EXPERIMENTAL INFECTION WITH Leishmania chagasi IN IMMUNOSUPPRESSED BALB/c MICE: CYTOKINES AND PARASITE BURDENS

Hoffmann JL (1), Machado JG (2), Gaio FC (2), Dias-Melicio LA (3), Langoni H (2)

(1) Department of Tropical Diseases, Botucatu Medical School, São Paulo State University, UNESP, Botucatu, São Paulo State, Brazil; (2) Zoonosis Research Center, NUPEZO, Veterinary Medicine and Animal Husbandry School, São Paulo State University, UNESP, Botucatu, São Paulo State, Brazil; (3) Department of Microbiology and Immunology, Botucatu Biosciences Institute, São Paulo State University, UNESP, Botucatu, São Paulo State, Brazil.

ABSTRACT: The immune response in leishmaniasis may result in a polarization of the T lymphocyte subpopulation, altering cell phenotype and resulting in immune protection or disease exacerbation. Leishmania may persist in the body either during asymptomatic infections or after treatment, which represents high risk under immunosuppression. The objective of this study was to evaluate the effect of infection with immunosuppression by dexamethasone associated with pentoxifylline on animal weight, spleen weight, spleen and hepatic parasitic load and immunopathology, as well as the IFN-g and IL-10 production in spleen cell culture of Balb/c mice infected with Leishmania chagasi. The infection did not cause body weight gain in animals, but both the weight and size of the spleen were increased. The immunosuppression using dexamethasone associated with pentoxifylline affected body weight gain and spleen weight and size in both infected and non-infected animals. The immunosuppression did not significantly alter the course of the splenic or hepatic parasite burden. Dexamethasone and pentoxifylline significantly affected cytokine production, but did not influence the Th1/Th2 ratio in infected animals.

KEY WORDS: Leishmania chagasI, immunosuppression, cell-mediated response, parasite burden, experimental infection.

CONFLITS OF INTERESTS: There is no conflict.

FINANCIAL SOURCE: FAPESP.

CORRESPONDENCE TO:

JULIANO LEÔNIDAS HOFFMANN, Departamento de Doenças Tropicais, Faculdade de Medicina de Botucatu, UNESP, Botucatu, SP, Brasil. Phone: +55 14 3811 6379. Fax: +55 14 3815 9898. Email: hoffmann1804@yahoo.com.br.