BackgroundTcTLE is a nonamer peptide from Trypanosoma cruzi KMP-11 protein that is conserved among different parasite strains and that is presented by different HLA-A molecules from the A2 supertype. Because peptides presented by several major histocompatibility complex (MHC) supertypes are potential targets for immunotherapy, the aim of this study was to determine whether MHC molecules other than the A2 supertype present the TcTLE peptide.Methodology/Principal FindingsFrom 36 HLA-A2-negative chagasic patients, the HLA-A genotypes of twenty-eight patients with CD8+ T cells that recognized the TcTLE peptide using tetramer (twenty) or functional (eight) assays, were determined. SSP-PCR was used to identify the A locus and the allelic variants. Flow cytometry was used to analyze the frequency of TcTLE-specific CD8+ T cells, and their functional activity (IFN-γ, TNFα, IL-2, perforin, granzyme and CD107a/b production) was induced by exposure to the TcTLE peptide. All patients tested had TcTLE-specific CD8+ T cells with frequencies ranging from 0.07–0.37%. Interestingly, seven of the twenty-eight patients had HLA-A homozygous alleles: A*24 (5 patients), A*23 (1 patient) and A*01 (1 patient), which belong to the A24 and A1 supertypes. In the remaining 21 patients with HLA-A heterozygous alleles, the most prominent alleles were A24 and A68. The most common allele sub-type was A*2402 (sixteen patients), which belongs to the A24 supertype, followed by A*6802 (six patients) from the A2 supertype. Additionally, the A*3002/A*3201 alleles from the A1 supertype were detected in one patient. All patients presented CD8+ T cells producing at least one cytokine after TcTLE peptide stimulation.Conclusion/SignificanceThese results show that TcTLE is a promiscuous peptide that is presented by the A24 and A1 supertypes, in addition to the A2 supertype, suggesting its potential as a target for immunotherapy.

Flow cytometry (FCM) was implemented in 2008 at the Pontificia Universidad Javeriana and later at the Hospital Universitario San Ignacio to examine special samples of patients with hematological malignancies and solid tumors other than bone marrow and peripheral blood for diagnosis and monitoring. This study describes the main findings of special sample evaluation over a six-year period. In all, 1070 samples of body fluids from patients with benign and malignant diseases were examined by FCM. These samples were stabilized with TransFix TM and stained with six-color immunophenotyping panels. Samples included cerebrospinal fluid, bronchoalveolar lavage, pleural fluid, pericardial fluid and ascite fluid from patients with acute and chronic leukemia, myelodysplastic syndromes, lymphomas, myeloma, autoimmune diseases, immunodeficiencies and solid tumors, among others. Flow cytometry provided important information for the classification and detection of minimal numbers of tumor cells in leukemia and lymphoma cases. This work represents the first national report describing FCM implementation in special samples for diagnosis and clinical monitoring of patients with malignant and benign pathologies. Consequently, over the last decade, use of commercially available cell stabilization solutions has been recommended. These solutions can preserve PB and cerebrospinal fluid (CSF) samples over time periods greater than one week after collection [4, 8 -9]. This stabilization preserves cellularity and integrity of both cell surface and intracellular antigens [9].

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