The α/β T cell repertoire is made up of T cells expressing diverse T cell receptors (TCR) composed of disulphide-bound α and β TCR chains. These TCR recognize antigens as peptides

bound to major histocompatibility complex (MHC) molecules [16] that, together with co-stimulatory molecules, develop an effective immune response [17]. The α and β chains are the most common among peripheral T cells and are composed of subregions V and J, or V, D and J, respectively, which combine to provide the TCR’s fine specificity. Antigen recognition DAPT mw diversity is generated in part by the use of specific V region gene segments encoding for each polypeptide chain of the TCR [18,19]. Furthermore, study of the T cell receptor (TCR) repertoire can contribute to understanding disease pathogenesis and, for this reason, has been an important focus of research in several diseases [20–22]. Studies of the TCR Vβ repertoire have also described the role played by microbial toxins or superantigens in activating the human immune system [23,24]. Superantigen stimulation of the immune system or stimulation by dominant antigens leads to proliferation of specific T cell

populations followed by clonal Caspase phosphorylation deletion [25]. In human leishmaniasis, the adaptive immune response is predominantly T cell-mediated. It has been demonstrated that the predominant T cells in CL lesions bear the αβ TCR [26,27]. Studies using polymerase chain reaction (PCR) in CL patient lesions caused by L. braziliensis have demonstrated

that the TCR Vβ repertoire presented expansions of Vβ families 3, 6·6/6·7 and 7 in 50% of the patients studied; however, as CD4+ and CD8+ T cells were not separated, interpretation of what proportion of these dominant responses are due to CD4+ or CD8+ or both is impossible [28]. Another study has shown an expansion of CD4+ and CD8+ T cells expressing Vβ 12 after stimulation with soluble Leishmania antigen (SLA) of L. amazonensis among CL Phospholipase D1 patients infected with L. braziliensis, and thus points to this population as a dominant responding population in this disease [29]. Specific subpopulations of T cells can be identified using monoclonal antibodies directed against the TCR β chain region and thus, using flow cytometry, we are able to examine the relative frequency, activation state and functional activity of these populations either ex vivo or after specific antigenic stimulation in vitro. Eventually, through the identification of specific T cell populations involved in the response, we can use this information to identify antigens involved in the response against Leishmania.