Host immune response against Mycobacterium tuberculosis is mediated by cellular immunity, in which cytokines and Th1 cells play a critical role. In the process of control of the infection by mycobacteria, TNF-alpha seems to have a primordial function. This cytokine acts in synergy with IFN-gamma, stimulating the production of reactive nitrogen intermediates (RNIs), thus mediating the tuberculostatic function of macrophages, and also stimulating the migration of immune cells to the infection site, contributing to granuloma formation, which controls the disease progression. IFN-gamma is the main cytokine involved in the immune response against mycobacteria, and its major function is the activation of macrophages, allowing them to exert its microbicidal role functions. Different from TNF-alpha and IFN-gamma, IL-10 is considered primarily an inhibitory cytokine, important to an adequate balance between inflammatory and immunopathologic responses. The increase in IL-10 levels seems to support the survival of mycobacteria in the host. Although there is not yet conclusive studies concerning a clear dichotomy between Th1 and Th2 responses, involving protective immunity and susceptibility to the disease, respectively, we can suggest that the knowledge about this responses based on the prevailing cytokine profile can help to elucidate the immune response related to the protection against M. tuberculosis.

American cutaneous leishmaniasis (ACL) has different clinical manifestations and these manifestations are dependent on the immunological status of the host. As CD4(+) and CD8(+) T cells and their mediators play a fundamental role in the host response to Leishmania and there is also a search for antigenic molecules to be used as future vaccines and tools for prognostic tests, this study characterized ACL patients' immune response after stimulation with soluble and insoluble fractions of L. (V.) braziliensis. We demonstrated a prevailing production of the Th2 cytokines, IL-4 and IL-10 and a specific production of IFN-γ and TNF-α in patients before treatment. There was also a predominance of CD4(+) T cells and a small percentage CD8(+) T cells. The insoluble antigenic fraction primarily stimulated CD4(+) T cells, while the soluble antigenic fraction showed a mixed profile, with CD4(+) T cells being the main responsible for Th2 cytokines and CD8(+) T cells for Th1 cytokines. Therefore, our results showed that a down-modulation of the Th1 type of response occurs in the initial phase of L. braziliensis disease, being the antigenic fractions capable of stimulating a specific immune response.

American cutaneous leishmaniasis (ACL) has different clinical manifestations and those are dependent on the immunological status of the host. Since CD4 + and CD8 + T cells and its mediators play a fundamental role in the host response to Leishmania and that there is also a search for antigenic molecules to be used as future vaccines and tools for prognostic tests, this study characterized ACL patients immune response after stimulation with soluble and insoluble fractions of L. (V.) braziliensis. We demonstrated a prevailing production of the Th2 cytokines, IL-4 and IL-10, and a specific production of IFN-γ and TNF-α in patients before treatment. There was also a predominance of CD4 + T cells and a small percentage CD8 + T cells. The insoluble antigenic fraction primarily stimulated CD4 + T cells while the soluble antigenic fraction showed a mixed profile, with CD4 + T cells being the main responsible for Th2 cytokines and CD8 + T cells for Th1 cytokines. Therefore, our results showed that a down modulation of the Th1 type of response occurs in the initial phase of L. braziliensis disease being the antigenic fractions capable of stimulating a specific immune response.