Antigenic fractions of Leishmania (Viannia) braziliensis: the immune response characterization of patients at the initial phase of disease.

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.