scholarly journals Self-reactive human CD4 T cell clones form unusual immunological synapses

2012 ◽  
Vol 209 (2) ◽  
pp. 335-352 ◽  
Author(s):  
David A. Schubert ◽  
Susana Gordo ◽  
Joseph J. Sabatino ◽  
Santosh Vardhana ◽  
Etienne Gagnon ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Receptor ◽  
Tcr Signaling ◽  
T Cell Clones ◽  
Cell Clones ◽  
Immunological Synapses ◽  
High Degree ◽  
Self Antigen

Recognition of self–peptide-MHC (pMHC) complexes by CD4 T cells plays an important role in the pathogenesis of many autoimmune diseases. We analyzed formation of immunological synapses (IS) in self-reactive T cell clones from patients with multiple sclerosis and type 1 diabetes. All self-reactive T cells contained a large number of phosphorylated T cell receptor (TCR) microclusters, indicative of active TCR signaling. However, they showed little or no visible pMHC accumulation or transport of TCR–pMHC complexes into a central supramolecular activation cluster (cSMAC). In contrast, influenza-specific T cells accumulated large quantities of pMHC complexes in microclusters and a cSMAC, even when presented with 100-fold lower pMHC densities. The self-reactive T cells also maintained a high degree of motility, again in sharp contrast to virus-specific T cells. 2D affinity measurements of three of these self-reactive T cell clones demonstrated a normal off-rate but a slow on-rate of TCR binding to pMHC. These unusual IS features may facilitate escape from negative selection by self-reactive T cells encountering very small amounts of self-antigen in the thymus. However, these same features may enable acquisition of effector functions by self-reactive T cells encountering large amounts of self-antigen in the target organ of the autoimmune disease.

scholarly journals Diversification of the antigen-specific T cell receptor repertoire after varicella zoster vaccination

2016 ◽  
Vol 8 (332) ◽  
pp. 332ra46-332ra46 ◽  
Author(s):  
Qian Qi ◽  
Mary M. Cavanagh ◽  
Sabine Le Saux ◽  
Hong NamKoong ◽  
Chulwoo Kim ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Chronic Infection ◽  
Cell Receptor ◽  
Control Mechanisms ◽  
Cell Repertoire ◽  
T Cell Clones ◽  
Varicella Zoster ◽  
Cell Clones

Diversity and size of the antigen-specific T cell receptor (TCR) repertoire are two critical determinants for successful control of chronic infection. Varicella zoster virus (VZV) that establishes latency during childhood can escape control mechanisms, in particular with increasing age. We examined the TCR diversity of VZV-reactive CD4 T cells in individuals older than 50 years by studying three identical twin pairs and three unrelated individuals before and after vaccination with live attenuated VZV. Although all individuals had a small number of dominant T cell clones, the breadth of the VZV-specific repertoire differed markedly. A genetic influence was seen for the sharing of individual TCR sequences from antigen-reactive cells but not for repertoire richness or the selection of dominant clones. VZV vaccination favored the expansion of infrequent VZV antigen–reactive TCRs, including those from naïve T cells with lesser boosting of dominant T cell clones. Thus, vaccination does not reinforce the in vivo selection that occurred during chronic infection but leads to a diversification of the VZV-reactive T cell repertoire. However, a single-booster immunization seems insufficient to establish new clonal dominance. Our results suggest that repertoire analysis of antigen-specific TCRs can be an important readout to assess whether a vaccination was able to generate memory cells in clonal sizes that are necessary for immune protection.

ROR1 Specific T Cell Clones from Healthy Individuals Show Common T Cell Receptor Motifs

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3364-3364
Author(s):  
Falk Heidenreich ◽  
Elke Ruecker-Braun ◽  
Juliane S. Stickel ◽  
Anne Eugster ◽  
Denise Kühn ◽  
...  
Keyword(s):  
Amino Acids ◽  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
T Cell Receptor ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
Cell Receptor ◽  
T Cell Clones ◽  
Cell Clones

Abstract Background Immunotherapy for CLL with new antibodies or T-cells with modified TCR relies on attractive targets. ROR1 is such a promising target since it is highly overexpressed in CLL. Chimeric antigen receptor engineered T cells and antibodies directed against the extracellular part of ROR1 have already been developed and tested in vitro or in animal models, but still there is no MHC-class I presented peptide serving as target structure for CD8+ T cells (with or without a genetically modified T cell receptor) available. Aim The aim of this study was (1) to identify an immunogenic MHC-class I presented ROR1 peptide, (2) to generate respective ROR1 peptide specific CD8+ T cell clones, and (3) to analyze the nucleotide sequence of the CDR3 region of the expressed alpha and beta T cell receptor chain. Results In mass spectrometric-based analyses of the HLA-ligandome a HLA-B*07 presented ROR1 peptide was identified in primary CLL cells of two patients. Six T cell clones specific for this particular ROR1-peptide were generated from single CD8+ T cells from 2 healthy individuals with 3 T cell clones generated from each donor. Functionality and specificity of those T cell clones were tested in cytotoxicity assays. All 6 dextramer+ CD8+ T cell clones lysed peptide loaded and HLA-B*07+ transduced K562 cells (kindly provided by Lorenz Jahn, [Jahn et al., Blood, 2015 Feb 5;125(6):949-58]). Two selected clones (XD8 and XB6) were tested for their cytotoxic potential against 2 ROR1+ HLA-B*07+ tumor cell lines (with the ROR1 peptide identified by mass spectrometry for both of them) and against 2 primary CLL cell samples. Tested clones showed a significant lysis of the respective target cells. CDR3 regions of the alpha and beta T cell receptor chain were sequenced on a single cell level. The CDR3 alpha region from each of the 3 ROR1 specific T cell clones from donor A showed some similarities to T cell clones derived from donor B (Table 1). Conclusion For the first time a MHC-class I presented ROR1 peptide antigen is reported. ROR1 positive CLL cells can be targeted by specific HLA-B*07 restricted CTLs. Respective CD8+ T cell clones with anti-leukemic activity from 2 donors share some amino acid motifs of the CDR3 alpha and beta regions. In conclusion, this information provides the possibility of generating ROR1 specific CD8+ T cells with genetically modified T cell receptors for immunotherapy and for tracking those cells after administration with next generation sequencing in peripheral blood samples of patients. Furthermore, data suggest the existence of public TCR motifs in leukemia antigen specific CTLs, which needs to be proven in follow-up experiments with larger cohorts of donors and patients. Finally, the presented strategy to identify leukemia specific peptide antigens for CD8+ T cells might be an attractive method for similar projects. Table 1 Amino acid sequences of CDR3 alpha and beta regions of the TCR of ROR1 specific CD8+ T cell clones. When comparing two clones, matching amino acids are depicted in red. The aromatic amino acids phenylalanine (F) and tyrosine (Y) are shown in blue when situated at the same position. Gaps inserted during the sequence alignment process are indicated by a hyphen '-'. Table 1. Amino acid sequences of CDR3 alpha and beta regions of the TCR of ROR1 specific CD8+ T cell clones. When comparing two clones, matching amino acids are depicted in red. The aromatic amino acids phenylalanine (F) and tyrosine (Y) are shown in blue when situated at the same position. Gaps inserted during the sequence alignment process are indicated by a hyphen '-'. Disclosures Middeke: Sanofi: Honoraria. Schetelig:Sanofi: Honoraria.

scholarly journals Analysis of T cell receptor beta chains in Lewis rats with experimental allergic encephalomyelitis: conserved complementarity determining region 3.

1991 ◽  
Vol 174 (6) ◽  
pp. 1467-1476 ◽  
Author(s):  
D P Gold ◽  
H Offner ◽  
D Sun ◽  
S Wiley ◽  
A A Vandenbark ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lymph Nodes ◽  
Cell Receptor ◽  
Fetal Life ◽  
Allergic Encephalomyelitis ◽  
T Cell Clones ◽  
Lewis Rats ◽  
Cell Clones ◽  
Complementarity Determining Region

This study explores the usage of T cell antigen receptor (TCR) beta chain elements in Lewis rats with experimentally induced allergic encephalomyelitis (EAE). TCRs from 15 different T cell clones and hybridomas derived from animals immunized with myelin basic protein (MBP), and all having specificity for the 21-mer encephalitogenic fragment MBP 68-88, utilized V beta 8.2. In addition, there was a marked conservation of the first two amino acid residues of the junctional complementarity determining region 3 (CDR3) associated with the V beta 8.2 receptors. 12 of 15 contained an aspartic acid followed by serine regardless of the associated J beta element. At the nucleotide level, this conservation of AspSer residues was accomplished with few or no nongermline-encoded nucleotide (N) additions. A similar pattern of AspSer usage and N region nucleotide additions was observed in a number of V beta 8.2 isolates derived from MBP-immunized lymph nodes. In contrast, V beta 8.2 polymerase chain reaction amplified isolates from Lewis T cells activated with concanavalin A or from lymph nodes of complete Freund's adjuvant-immunized animals showed no AspSer utilization (0/31) in the CDR3, and four to nine N region nucleotide additions. We conclude from this finding that AspSer residues in the CDR3, limited N region nucleotide additions, along with V beta 8.2 sequences, contribute to TCR specificity for MBP 68-88. This raises the possibility that encephalitogenic, disease-causing T cells either represent a population that derives from late fetal life or alternatively, that they are rare cells with this particular TCR phenotype contributed to the T cell pool throughout adulthood and are selected by antigen. In either case, the CDR3 AspSer sequences as well as V beta 8.2 sequences are candidates for the receptor target structures recognized by regulator T cells in recovery from and resistance to active EAE. In this respect, a preliminary analysis of TCR utilization in three T cell clones specific for MBP 68-88 isolated from animals recovered from active EAE indicates that while all three use V beta 8.2, only one contains AspSer in the CDR3.

scholarly journals Selection of a human T helper type 1-like T cell subset by mycobacteria.

1991 ◽  
Vol 174 (3) ◽  
pp. 583-592 ◽  
Author(s):  
J B Haanen ◽  
R de Waal Malefijt ◽  
P C Res ◽  
E M Kraakman ◽  
T H Ottenhoff ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cytokine Secretion ◽  
T Helper ◽  
Ifn Gamma ◽  
T Cell Clones ◽  
Cell Clones ◽  
Tuberculoid Leprosy ◽  
Helper Type

Mycobacteria elicit a cellular immune response in their hosts. This response usually leads to protective immunity, but may sometimes be accompanied by immunopathology due to delayed type hypersensitivity (DTH). A striking example in man is tuberculoid leprosy, which is characterized by high cellular immunity to Mycobacterium leprae and immunopathology due to DTH. Skin lesions of patients suffering from this disease have the characteristics of DTH reactions in which macrophages and CD4+ T lymphocytes predominate. In animal models, it has been shown that DTH responses are associated with the presence of a particular subset of CD4+ T cells (T helper type 1 [Th1]) that secrete only certain cytokines, such as interleukin 2 (IL-2), interferon gamma (IFN-gamma), and lymphotoxin, but no IL-4 or IL-5. We studied the cytokine release of activated M. leprae-reactive CD4+ T cell clones derived from tuberculoid leprosy patients. These T cell clones, which were reactive with mycobacterial heat shock proteins, exhibited a Th1-like cytokine secretion pattern with very high levels of IFN-gamma. Half of these clones secreted low levels of IL-4 and IL-5, but the ratio of IFN-gamma to IL-4 and IL-5 was much higher than that of T cell clones reactive with nonmycobacterial antigens. A Th1-like cytokine secretion pattern was also observed for T cell clones and polyclonal T cell lines from control individuals that recognized both heat shock and other mycobacterial antigens. The levels of IFN-gamma secreted by these clones were, however, significantly less than those of patient-derived T cell clones. This Th1-like pattern was not found with T cell clones from the same patients and healthy individuals generated in the same manner, but reactive with nonmycobacterial antigens. Our data thus indicate that mycobacteria selectively induce human T cells with a Th1-like cytokine secretion profile.

scholarly journals Different Levels of T-Cell Receptor Triggering Induce Distinct Functions in Hepatitis B and Hepatitis C Virus-Specific Human CD4+ T-Cell Clones

2001 ◽  
Vol 75 (17) ◽  
pp. 7803-7810 ◽  
Author(s):  
Helmut M. Diepolder ◽  
Norbert H. Gruener ◽  
J. Tilman Gerlach ◽  
Maria-Christina Jung ◽  
Eddy A. Wierenga ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Specific Antigen ◽  
Cell Receptor ◽  
Receptor Internalization ◽  
Antigen Concentration ◽  
T Cell Clones ◽  
Cell Clones ◽  
Wide Range

ABSTRACT CD4+ T cells play a major role in the host defense against viruses and intracellular microbes. During the natural course of such an infection, specific CD4+ T cells are exposed to a wide range of antigen concentrations depending on the body compartment and the stage of disease. While epitope variants trigger only subsets of T-cell effector functions, the response of virus-specific CD4+ T cells to various concentrations of the wild-type antigen has not been systematically studied. We stimulated hepatitis B virus core- and hepatitis C virus NS3-specific CD4+ T-cell clones which had been isolated from patients with acute hepatitis during viral clearance with a wide range of specific antigen concentrations and determined the phenotypic changes and the induction of T-cell effector functions in relation to T-cell receptor internalization. A low antigen concentration induced the expression of T-cell activation markers and adhesion molecules in CD4+ T-cell clones in the absence of cytokine secretion and proliferation. The expression of CD25, HLA-DR, CD69, and intercellular cell adhesion molecule 1 increased as soon as T-cell receptor internalization became detectable. A 30- to 100-fold-higher antigen concentration, corresponding to the internalization of 20 to 30% of T-cell receptor molecules, however, was required for the induction of proliferation as well as for gamma interferon and interleukin-4 secretion. These data indicate that virus-specific CD4+ T cells can respond to specific antigen in a graded manner depending on the antigen concentration, which may have implications for a coordinate regulation of specific CD4+ T-cell responses.

scholarly journals Mobilization of pre-existing polyclonal T cells specific to neoantigens but not self-antigens during treatment of a patient with melanoma with bempegaldesleukin and nivolumab

2020 ◽  
Vol 8 (2) ◽  
pp. e001591
Author(s):  
Joshua R Veatch ◽  
Naina Singhi ◽  
Brenda Jesernig ◽  
Kelly G Paulson ◽  
Jonathan Zalevsky ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Interleukin 2 ◽  
Interferon Γ ◽  
Immune Checkpoint Blockade ◽  
Tumor Rejection ◽  
T Cell Clones ◽  
Cell Clones ◽  
Self Antigen ◽  
Self Antigens

T cells that recognize self-antigens and mutated neoantigens are thought to mediate antitumor activity of immune checkpoint blockade (ICB) in melanoma. Few studies have analyzed self and neoantigen-specific T cell responses in patients responding to ICB. Here, we report a patient with metastatic melanoma who had a durable clinical response after treatment with the programmed cell death protein 1 inhibitor, nivolumab, combined with the first-in-class CD122-preferential interleukin-2 pathway agonist, bempegaldesleukin (BEMPEG, NKTR-214). We used a combination of antigen-specific T cell expansion and measurement of interferon-γ secretion to identify multiple CD4+ and CD8+ T cell clones specific for neoantigens, lineage-specific antigens and cancer testis antigens in blood and tumor from this patient prior to and after therapy. Polyclonal CD4+ and CD8+ T cells specific to multiple neoantigens but not self-antigens were highly enriched in pretreatment tumor compared with peripheral blood. Neoantigen, but not self-antigen-specific T cell clones expanded in frequency in the blood during successful treatment. There was evidence of dramatic immune infiltration into the tumor on treatment, and a modest increase in the relative frequency of intratumoral neoantigen-specific T cells. These observations suggest that diverse CD8+ and CD4+ T cell clones specific for neoantigens present in tumor before treatment had a greater role in immune tumor rejection as compared with self-antigen-specific T cells in this patient. Trial registration number: NCT02983045.

scholarly journals Strong Ability of Nef-Specific CD4+ Cytotoxic T Cells To Suppress Human Immunodeficiency Virus Type 1 (HIV-1) Replication in HIV-1-Infected CD4+ T Cells and Macrophages

2009 ◽  
Vol 83 (15) ◽  
pp. 7668-7677 ◽  
Author(s):  
Nan Zheng ◽  
Mamoru Fujiwara ◽  
Takamasa Ueno ◽  
Shinichi Oka ◽  
Masafumi Takiguchi
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
T Cell ◽  
Human Immunodeficiency Virus Type ◽  
T Cell Clones ◽  
Cell Clones ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Strong Ability

ABSTRACT A restricted number of studies have shown that human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic CD4+ T cells are present in HIV-1-infected individuals. However, the roles of this type of CD4+ T cell in the immune responses against an HIV-1 infection remain unclear. In this study, we identified novel Nef epitope-specific HLA-DRB1*0803-restricted cytotoxic CD4+ T cells. The CD4+ T-cell clones specific for Nef187-203 showed strong gamma interferon production after having been stimulated with autologous B-lymphoblastoid cells infected with recombinant vaccinia virus expressing Nef or pulsed with heat-inactivated virus particles, indicating the presentation of the epitope antigen through both exogenous and endogenous major histocompatibility complex class II processing pathways. Nef187-203-specific CD4+ T-cell clones exhibited strong cytotoxic activity against both HIV-1-infected macrophages and CD4+ T cells from an HLA-DRB1*0803+ donor. In addition, these Nef-specific cytotoxic CD4+ T-cell clones exhibited strong ability to suppress HIV-1 replication in both macrophages and CD4+ T cells in vitro. Nef187-203-specific cytotoxic CD4+ T cells were detected in cultures of peptide-stimulated peripheral blood mononuclear cells (PBMCs) and in ex vivo PBMCs from 40% and 20% of DRB1*0803+ donors, respectively. These results suggest that HIV-1-specific CD4+ T cells may directly control HIV-1 infection in vivo by suppressing virus replication in HIV-1 natural host cells.

scholarly journals Vβ1+ Jβ1.1+/Vα2+ Jα49+ CD4+ T Cells Mediate Resistance against Infection with Blastomyces dermatitidis

2006 ◽  
Vol 75 (1) ◽  
pp. 193-200 ◽  
Author(s):  
Marcel Wüthrich ◽  
Hanna I. Filutowicz ◽  
Holly L. Allen ◽  
George S. Deepe ◽  
Bruce S. Klein
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Receptor ◽  
Blastomyces Dermatitidis ◽  
T Cell Clones ◽  
Interleukin 5 ◽  
Protective Antigens ◽  
Cell Clones ◽  
A Cell ◽  
Ifn Γ

ABSTRACT Immunization with a cell wall/membrane (CW/M) and yeast cytosol extract (YCE) crude antigen from Blastomyces dermatitidis confers T-cell-mediated resistance against lethal experimental infection in mice. We isolated and characterized T cells that recognize components of these protective antigens and mediate protection. CD4+ T-cell clones elicited with CW/M antigen adoptively transferred protective immunity when they expressed a Vα2+ Jα49+/Vβ1+ Jβ1.1+ heterodimeric T-cell receptor (TCR) and produced high levels of gamma interferon (IFN-γ). In contrast, Vβ8.1/8.2+ CD4+ T-cell clones that were reactive against CW/M and YCE antigens and produced little or no IFN-γ either failed to mediate protection or exacerbated the infection depending on the level of interleukin-5 expression. Thus, the outgrowth of protective T-cell clones against immunodominant antigens of B. dermatitidis is biased by a combination of the TCR repertoire and Th1 cytokine production.

scholarly journals T-Cell Receptor (TCR) Clonotype-Specific Differences in Inhibitory Activity of HIV-1 Cytotoxic T-Cell Clones Is Not Mediated by TCR Alone

2017 ◽  
Vol 91 (6) ◽  
Author(s):  
Nina C. Flerin ◽  
Huabiao Chen ◽  
Tynisha D. Glover ◽  
Pedro A. Lamothe ◽  
Jian Hua Zheng ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Function ◽  
Signal Propagation ◽  
Cell Receptor ◽  
Elite Controllers ◽  
T Cell Clones ◽  
Cell Clones ◽  
Lytic Granule ◽  
Hiv 1

ABSTRACT Functional analysis of T-cell responses in HIV-infected individuals has indicated that virus-specific CD8+ T cells with superior antiviral efficacy are well represented in HIV-1 controllers but are rare or absent in HIV-1 progressors. To define the role of individual T-cell receptor (TCR) clonotypes in differential antiviral CD8+ T-cell function, we performed detailed functional and mass cytometric cluster analysis of multiple CD8+ T-cell clones recognizing the identical HLA-B*2705-restricted HIV-1 epitope KK10 (KRWIILGLNK). Effective and ineffective CD8+ T-cell clones segregated based on responses to HIV-1-infected and peptide-loaded target cells. Following cognate peptide stimulation, effective HIV-specific clones displayed significantly more rapid TCR signal propagation, more efficient initial lytic granule release, and more sustained nonlytic cytokine and chemokine secretion than ineffective clones. To evaluate the TCR clonotype contribution to CD8+ T-cell function, we cloned the TCR α and β chain genes from one effective and two ineffective CD8+ T-cell clones from an elite controller into TCR-expressing lentivectors. We show that Jurkat/MA cells and primary CD8+ T cells transduced with lentivirus expressing TCR from one of the ineffective clones exhibited a level of activation by cognate peptide and inhibition of in vitro HIV-1 infection, respectively, that were comparable to those of the effective clonotype. Taken together, these data suggest that the potent antiviral capacity of some HIV-specific CD8+ T cells is a consequence of factors in addition to TCR sequence that modulate functionality and contribute to the increased antiviral capacity of HIV-specific CD8+ T cells in elite controllers to inhibit HIV infection. IMPORTANCE The greater ex vivo antiviral inhibitory activity of CD8+ T cells from elite controllers than from HIV-1 progressors supports the crucial role of effective HIV-specific CD8+ T cells in controlling HIV-1 replication. The contribution of TCR clonotype to inhibitory potency was investigated by delineating the responsiveness of effective and ineffective CD8+ T-cell clones recognizing the identical HLA-B*2705-restricted HIV-1 Gag-derived peptide, KK10 (KRWIILGLNK). KK10-stimulated “effective” CD8+ T-cell clones displayed significantly more rapid TCR signal propagation, more efficient initial lytic granule release, and more sustained cytokine and chemokine secretion than “ineffective” CD8+ T-cell clones. However, TCRs cloned from an effective and one of two ineffective clones conferred upon primary CD8+ T cells the equivalent potent capacity to inhibit HIV-1 infection. Taken together, these data suggest that other factors aside from intrinsic TCR-peptide-major histocompatibility complex (TCR-peptide-MHC) reactivity can contribute to the potent antiviral capacity of some HIV-specific CD8+ T-cell clones.

Molecular Identification of Individual T Cell Clones Specific for Graft- Versus-Leukemia Reaction

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1249-1249
Author(s):  
Veronika Foltankova ◽  
Eva Matejkova ◽  
Milan Bartos ◽  
Milos Dendis ◽  
Dana Novotna ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mononuclear Cells ◽  
Cell Clone ◽  
Cell Receptor ◽  
Unique Sequence ◽  
Hematopoietic Stem ◽  
T Cell Clones ◽  
Cell Clones ◽  
T Cell Clone

Abstract Graft-verus-leukemia (GVL) effect in hematopoietic stem cell transplantation (HSCT) is usually complicated by the alloreactivity of donor T cells which leads to acute graft-versus-host (GVH) disease. GVL and GVH reactions are proved to be mediated by different T cell clones. The objective of this study was to identify and characterize T cells clones with specific antileukemia activity without mediating GVHD. We have performed primary mixed leukocyte reaction (MLR) using patient non-leukemic irradiated peripherial blood mononuclear cells (PBMC) as stimulators and donor PBMC as responders. To prepare GVL specific T cells, activated alloreactive T cells were first selectively depleted with an anti-CD25 immunotoxin (Michalek, et al. PNAS2003, 100: 1180–4). Allodepleted T cells were then stimulated in secondary MLR using irradiated leukemia cells from the same patient. Activated leukemia-reactive cells were purified by immunomagnetic selection or by FACS based on INF-γ or CD25 expression, respectively. Clonotypic assay was used for identification of individual leukemia-specific T cell clones (Michalek, et al. Lancet2003, 361: 1183–5; Michalek, et al. J Immunol2007, 178: 6789– 5). This highly sensitive assay is based on detailed analysis of T cell receptor β VDJ unique sequence (TCRB-VDJ). mRNA was extracted from sortred activated cells and cDNA synthetized by anchored reverse transcription. Target TCRB-VDJ gene sequence was amplified by anchor PCR and used to transform bacteria. Bacterial colonies were picked for plasmid isolation and subsequent direct automated sequencing of the TCRBVDJ sequences. We assume that the frequency of particular TCRB-VDJ sequences among bacterial clones after transformation are proportional to the frequency of those sequences in the original population of T cells activated by GVH or GVL reaction. We investigated the presence of individual antileukemic T cell clones in patients with acute myeloid leukemia (AML) and chronic lymphatic leukemia (CLL), and defined them by the TCRB-VDJ unique sequence. The sequences that occured in more than 10% bacterial colonies are likely to represent the most immunodominant clones. Populations of antileukemic T cell clones were oligoclonal, i.e. we observed limited number of individual immunodominat clones which plays important role in GVL reaction. In first CLL patient who had undergone HSCT, six antileukemic T cell clones were identified, four of them are considered to be immunodominant. In second CLL patient after HSCT, only one highly immunodominat autileukemic T cell clone was observed. This specific clone was further monitored by quantitative real-time PCR in patients peripherial blood.

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