Background. Trypanosoma cruzi infection is induced by triatomine contaminated feces containing metacyclic trypomastigotes acquired via small wounds in the skin. Natural unspecific and adaptive humoral and cellular immune responses play an important role in controling primary infection.
Objective: To determine the cytokine profile at the inoculation site and nearby tissues such as draining lymph nodes, as well as the heart and serum, throughout the acute and chronic phases in mice infected with metacyclic T. cruzi trypomastigotes.
Material and methods. Balc⁄c mice were intradermally inoculated with vector derived metacyclic trypomastigotes of T. cruzi. The RT-PCR technique was used to analyze the cytokine profile at the inoculation site, draining lymph nodes and heart. ELISA was used to determine cytokines in serum.
Results. A poor induction of cytokines within the two weeks after infection such as IL-12, IFN-gamma, IL-4, IL-10 and TGF-beta and undetectable IL-2 was observed at the inoculation site. On the other hand, in draining lymph nodes, cytokines such as IL-2, IL-10, IL-12, TGF-beta were detected from the first day after infection. In the heart, a mixed inflammatory and anti-inflammatory cytokine pattern was identified. In serum, all cytokines tested (IL-4, IL-10 IL-12 and IFN-gamma) were detected from the 5^th day post-infection with the notorious exception of IL-2. Conclusion. A poor and late induction of protective cytokines such as IFN-gamma and IL-12 was observed at the inoculation site, in spite of adequate immune responses in lymph nodes. In addition, the pattern of cytokine expression strongly depended on the kind of tissue.