Evaluación de un método para el aislamiento de péptidos naturales de “Leishmania spp”.

Evaluation of a Method for the Leishmania spp Natural Peptide IsolationThe ability of macrophages to process and present Leishmania antigens is thought to be needed for theirefficient interaction with effector T cells and locally-delivered cytokines which induce a leishmanicidalactivity. T cell receptors (TCR) recognize antigenic peptides associated with the major histocompatibilitycomplex (MHC) molecules, and this trimolecular interaction initiates antigen-specific signaling pathways inthe responding T cells. In the development of vaccines for intracellular parasitic diseases, it is of pivotalimportance the elucidation of the immunological mechanisms associated with them, particularly, theidentification of peptides (T cell epitopes) that can stimulate a given TCR. Thus, we considered thepossibility of identifying natural Leishmania spp peptides able to stimulate T cell subpopulations thatproduce a pattern of cytokines associated with disease protection. As a first step in the study, we used amethod described by Malik and Strominger (2000), with significant modifications to isolate CMH/II-peptidecomplexes. For this purpose, a cell line of human monocytes were infected with promastigotesLeishmaniabraziliensis, and the expressed complexes were purified by immunoaffinity chromatography,and fractionated by RT-HPLC. The HPLC fractions obtained were tested for their capacity to stimulate a Tcell proliferative response and cytokine secretion. Results obtained from peripheral blood mononuclearcells (PBMC) from Leishmania-infected patients showed an important reactivity with two of the fractionstested, while the rest of the fractions were unable to induce cell stimulation with the strategy used.