T-Cells with Extremely Short Telomeres and High Telomerase Activity in T-Cell Prolymphocytic Leukemia (T-PLL): The Ideal Target for Telomerase Inhibition.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 497-497
Author(s):  
Alexander Roeth ◽  
Jan Duerig ◽  
Heike Himmelreich ◽  
Reiner Siebert ◽  
Stefanie Bug ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Telomere Length ◽  
Cell Clone ◽  
Telomerase Activity ◽  
Prolymphocytic Leukemia ◽  
Telomerase Inhibitor ◽  
T Cell Clone

Abstract T-cell prolymphocytic leukemia (T-PLL) is a rare aggressive lymphoproliferative disease characterized by the expansion of a T-cell clone derived from immuno-competent post-thymic T-lymphocytes. Important mechanisms involved in expansion of human malignant cells are reactivation of telomerase, an enzyme complex, which is able to compensate the loss of telomere repeats by cell division, and maintenance or elongation of telomere length. To investigate the role of telomeres and telomerase we measured telomere length by automated multicolor flow-FISH and telomerase activity by telomeric repeat amplification protocol in subsets of peripheral blood leukocytes from 11 newly diagnosed or relapsed patients with sporadic T-PLL. In addition, we analyzed the effect of the selective telomerase inhibitor BIBR1532 on T-PLL cells in short-term culture assays. The average telomere length in the clonal T-cells of all samples analyzed was extremely short (mean ± std: 1.53 kb ± 0.65 kb) compared to the non-clonal T-cells (5.03 kb ± 0.71 kb; p=0.012). The average telomere length for B-cells in these patients was 6.37 kb ± 0.71 kb (n=6). Telomere length values of the clonal T-cells were all below the 1st percentile of telomere length values observed in T-cells from healthy aged-matched controls whereas non-clonal T-cells and B-cells fell between the 1st and 99th percentile of the normal distribution. Interestingly, telomere length in the clonal T-cells remained stably short at 1.0 kb ± 0.6 kb without further telomere loss in one patient over a period of 18 months. No cell doublets indicative of fused or bridged chromosomes and telomere dysfunction were observed. Clonal T-cells exhibited high levels of telomerase activity almost comparable to levels of the positive control K562 whereas there was no measurable telomerase activity in normal, unstimulated T-cells. Telomerase levels even correlated inversely with telomere length in clonal T-cells (r=−0.91, n=6). In addition, we could induce a dose-dependent cytotoxicity of T-PLL cells with the telomerase inhibitor BIBR1532 (viable cells as percentage of untreated controls (viability index) in % after 10 days of cell culture (mean ± std) with 0, 10, 40, 100 μM BIBR1532: 100 ± 0, 54 ± 14.3, 27.5 ± 11.7, 2.6 ± 1.6, n=6) whereas no effect was observed in normal, unstimulated T-cells (viability index in % (mean ± std) after 10 days with 0, 10, 40, 100 μM BIBR1532: 100 ± 0, 100.8 ± 8.6, 96.9 ± 7.9, 103.1 ± 22.4, n=3). In summary, clonal T-cells in T-PLL exhibit extremely short telomeres which could explain the genomic instability with cytogenetic aberrations. The high levels of telomerase found in T-PLL cells are sufficient to stably maintain the critically short telomeres and allow clonal expansion. In addition, we can demonstrate that inhibition of telomerase in vitro in the situation of T-PLL cells with already very short telomeres and high telomerase levels leads to rapid cytotoxicity of the T-cell clone without a time delay before telomeres get critically short as observed in the situation of longer telomeres. Targeting telomerase and telomeres seems therefore an attractive strategy for the future treatment of this devastating disease.

Immunotargetting of the Wilms’ Tumor WT1 Antigen for Dendritic Cell and B-Cell-Based Vaccination of Leukemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2541-2541
Author(s):  
Zwi N. Berneman ◽  
Ann Van Driessche ◽  
Peter Ponsaerts ◽  
Liquan Gao ◽  
Hans J. Stauss ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Dendritic Cell ◽  
Mhc Class I ◽  
Wilms Tumor ◽  
Cell Clone ◽  
Class I ◽  
T Cell Clone

Abstract The Wilms’ tumor antigen (WT1) is overexpressed in almost all leukemias and in several solid tumors. Overexpression of WT1 blocks the normal differentiation and enhances proliferation of hematopoietic progenitor cells. WT1 is also used in the detection of minimal residual disease. Using WT1-specific MHC class I tetramers, we were able to detect ex vivo low numbers of WT1-specific CD8+ T cells in the peripheral blood or bone marrow of leukemia patients, but not of healthy donors. In one particular donor we could detect up to 24% WT1 tetramer positive cells at the time of diagnosis. WT1 tetramer positive cells were present in all types of leukemia, except for CLL, and also in patients with MDS. Because WT1 plays an important role in leukemogenesis, it could serve as an antigenic target for dendritic cell-based immunotherapy. We used the mRNA electroporation strategy that allows presentation of multiple WT1 epitopes by MHC class I molecules, irrespective of the HLA haplotype. Monocyte-derived DC (Mo-DC) were electroporated with in vitro transcribed WT1 mRNA. RT-PCR and Western blot analysis showed that WT1 RNA and protein, respectively, was present for up to 5 days in WT1-electroporated DC, but not in mock- or EGFP mRNA-electroporated Mo-DC. Importantly, using a CD8+ T cell clone that secretes IFN-gamma upon recognizing the HLA-A2 immunodominant WT1126–134 epitope, we showed that WT1 mRNA-electroporated Mo-DC processed the WT1 protein via the MHC class I pathway and presented the WT1 epitope to the T cells in an HLA- and antigen-specific manner. Since Mo-DCs are a non-expandable source of antigen-presenting cells, we also used proliferating CD40-activated B (CD40-B) cells as inducers for WT1-specific T cell immunity. CD40-B cells were expanded to high numbers from a limited amount of peripheral blood and subsequently electroporated with WT1 mRNA. In T cell clone activation experiments, WT1 mRNA-electroporated CD40-B cells were as efficient as Mo-DC in presenting the WT1 epitope in a MHC class I-restricted manner. Based on these results, we are currently focusing on the in vitro (re)activation of autologous WT1-specific cytotoxic T cells of leukemia patients using WT1-loaded autologous Mo-DC or CD40-B cells and on the immunological parameters to break immune tolerance against the WT1 tumor self antigen.

scholarly journals IL4I1 Accelerates the Expansion of Effector CD8+ T Cells at the Expense of Memory Precursors by Increasing the Threshold of T-Cell Activation

2020 ◽  
Vol 11 ◽  
Author(s):  
Marie-Line Puiffe ◽  
Aurélie Dupont ◽  
Nouhoum Sako ◽  
Jérôme Gatineau ◽  
José L. Cohen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
Cell Clone ◽  
Cd8 T Cell ◽  
Lymphocytic Choriomeningitis ◽  
T Cell Clone

IL4I1 is an immunoregulatory enzyme that inhibits CD8 T-cell proliferation in vitro and in the tumoral context. Here, we dissected the effect of IL4I1 on CD8 T-cell priming by studying the differentiation of a transgenic CD8 T-cell clone and the endogenous repertoire in a mouse model of acute lymphocytic choriomeningitis virus (LCMV) infection. Unexpectedly, we show that IL4I1 accelerates the expansion of functional effector CD8 T cells during the first several days after infection and increases the average affinity of the elicited repertoire, supporting more efficient LCMV clearance in WT mice than IL4I1-deficient mice. Conversely, IL4I1 restrains the differentiation of CD8 T-cells into long-lived memory precursors and favors the memory response to the most immunodominant peptides. IL4I1 expression does not affect the phenotype or antigen-presenting functions of dendritic cells (DCs), but directly reduces the stability of T-DC immune synapses in vitro, thus dampening T-cell activation. Overall, our results support a model in which IL4I1 increases the threshold of T-cell activation, indirectly promoting the priming of high-affinity clones while limiting memory T-cell differentiation.

Maintenance of Telomere Length in Peripheral Blood CD4+CD25+ Regulatory T-Cells of Cancer Patients Despite Active Proliferation.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3309-3309
Author(s):  
Dominik Wolf ◽  
Holger Rumpold ◽  
Christian Koppelstaetter ◽  
Guenther Gastl ◽  
Eberhard Gunsilius ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Telomere Length ◽  
Cancer Patients ◽  
Peripheral Blood ◽  
Telomerase Activity ◽  
Telomere Shortening ◽  
Active Proliferation

Abstract CD4+CD25+ regulatory T-cells (Treg) are increased in the peripheral blood of cancer patients. It remains unclear whether this is due to redistribution or active proliferation. The latter would require the up-regulation of telomerase activity, whose regulation also remains unknown for Treg. We therefore isolated Treg and the respective CD4+CD25− control T-cell population from peripheral blood of cancer patients (n=23) and healthy age-matched controls (n=17). Analysis of their content of T-cell receptor excision circles (TREC) revealed that the observed increase of Treg frequencies in peripheral blood is due to active cycling rather than to redistribution from other compartments (i.e. secondary lymphoid organs or bone-marrow), as Treg from cancer patients are characterized by a significant decrease of TREC content when compared to TREC content of Treg isolated from healthy age-matched controls. Surprisingly, despite their proven in vivo proliferation, telomere length is not further shortened in Treg from peripheral blood of cancer patients as shown by Flow-Fish, Real-Time PCR and Southern Blotting. Accodingly, telomerase activity of Treg was readily inducible in vitro by OKT3 together with IL-2. Notably, sorting of in vitro proliferating Treg using dilution of CFSE revealed a significant telomere shortening in Treg with high proliferative capacity (i.e. CFSElow fraction) under conditions of strong in vitro stimulatory growth conditions despite a high telomerase activity. Thus, under conditions of strong in vitro stimulation induction of telomerase seems to be insufficient to avoid progressive telomere shortening. In contrast, in actively proliferating peripheral blood Treg from patients with epithelial malignancies induction of telomerase activity is likely to compensate for further telomere erosion.

Induction of ‘Tolerance’ in a T-Cell Clone from a Mild Hemophilia Patient

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3526-3526
Author(s):  
David W. Scott ◽  
Elizabeth Kadavil ◽  
Ai-Hong Zhang ◽  
Ruth A. Ettinger ◽  
Kathleen Pratt
Keyword(s):  
T Cell ◽  
B Cells ◽  
Hemophilia A ◽  
Cell Clone ◽  
Tolerance Induction ◽  
Hla Dr ◽  
Cell Clones ◽  
T Cell Clone ◽  
Pre Treatment

Abstract A major obstacle in the treatment of Hemophilia A is that patients can develop an inhibitory immune response to therapeutic doses of coagulation factor VIII (fVIII). Over the last decade, we have developed a B-cell delivered gene therapy approach to prevent the development of inhibitory antibodies (“inhibitors”) in fVIII knockout mice (see Lei and Scott, Blood105: 4865, 2005). In our murine platform, activated primary spleen B cells or bone marrow cells are transduced with a retroviral vector encoding the fVIII A2 and/or C2 domain fused to an IgG heavy chain, and these cells are injected systemically into immunocompetent fVIII knockout animals. The recipients are rendered specifically tolerant to the encoded C2 and A2 domains, as evidenced by a >90% reduction of inhibitor titers, even in primed animals. To help evaluate the potential of this approach for translation, we are developing in vitro models for tolerance induction using human T-cell clones isolated from subjects with mild hemophilia A. The clones are isolated by single-cell sorting of CD4+ cells that are labeled by fluorescent HLA-DR tetramers complexed with peptides containing fVIII epitopes, followed by expansion with HLA-DR mismatched peripheral blood mononuclear cells (PBMC), phytohaemagglutinin, and interleukin-2. Our initial model utilizes a T-cell clone from an individual with mild hemophilia A due to fVIII missense genotype A2201P, which recognizes an HLA-DRA-DRB1*0101-restricted epitope within a synthetic peptide corresponding to fVIII residues 2194–2213. All of the antigen-specific T-cell clones isolated from this subject secreted interferon-gamma (IFN-γ) when stimulated by fVIII2194–2213 presented by irradiated HLA-DR-matched PBMCs or with plate-bound anti-CD3. Because of their robust response to a clinically relevant epitope in fVIII, one of these clones that expanded well in culture was chosen for initial testing of a modified gene therapy platform similar to that developed using the murine hemophilia A model. HLA-matched peripheral blood B cells were activated with antibodies to IgM or with CD40L-expressing fibroblasts and then transduced with a modified retroviral vector containing the human C2 domain sequence in-frame with the IgG sequence. These B cells were cultured with the hemophilic T-cell clone. After pre-treatment (“tolerance-induction step”), the cells were washed and then stimulated by plate-bound anti-CD3. The subsequent IFN-γ response (measured by ELIspots and ELISA) was dramatically reduced compared to the response of same T-cell clone cultured with mock-transduced B cells. The post-treatment reduction in IFN-γ secretion was equivalent to that induced after soluble anti-CD3 pre-treatment, a known method to induce T-cell anergy in vitro. Interestingly, IL-10 was produced during the tolerance induction (pre-treatment) phase, most likely from the activated B cells. Preliminary, parallel experiments with B cells transduced with a “gutless” adenovirus vector expressing C2-Ig did not result in a similar down-regulation of the T-cell response, suggesting that this non-integrating method of expressing antigens for tolerance is not effective, at least in this system. These results are the first to demonstrate in vitro modulation of cytokine responses using DR-restricted, fVIII-specific T cells from a hemophilia A subject. Further investigations using T-cell clones from hemophilic subjects with and without anti-fVIII antibodies will allow us to explore mechanisms of tolerance and may also suggest novel approaches to reduce inhibitor titers.

Cytotoxicity Is Not Required for the Anti-Leukemia Efficacy of Human H-Y-Specific CD4+ T Lymphocytes In Vivo.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3553-3553
Author(s):  
Attilio Bondanza ◽  
Lothar Hambach ◽  
Zohara Aghai ◽  
Monica Casucci ◽  
Bart Nijmeijer ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cell Clone ◽  
Scid Mice ◽  
Helper T Cell ◽  
T Cell Clone ◽  
Control Clone

Abstract Abstract 3553 Poster Board III-490 Introduction Minor histocompatibility antigens (mHag) play a major role in the graft-versus-leukemia (GvL) effect following HLA-matched allogeneic hemopoietic cell transplantation (allo-HCT). Clinically, the GvL effect coincides with the emergence of mHag-specific CD8+ cytotoxic T lymphocytes (CTL). Experimentally, targeting a single mHag with human CD8+ CTL has a major anti-leukemia effect in NOD/scid mice. Altogether, these observations suggest that mHag-specific cytotoxicity by CD8+ T cells is an important component of the GvL effect. In contrast, little is known on the contribution of mHag-specific CD4+ T cells. Female-to-male allo-HCT is characterized by a low rate of leukemia relapse, indicating that H-Y-encoded mHag are potent leukemia-regression antigens. Earlier, we described a DRB3*0301-restricted H-Y mHag epitope inducing CD4+ helper T-cell responses in H-Y-mismatched HLA-matched allo-HCT. Aim: The aim of this study is to elucidate the role of mHag-specific human CD4+ T lymphocytes on the GvL effect. Methods The ALL-CM leukemia cell line, derived from a male (i.e. H-Y+) HLA-A0201+, DRB30301+ patient, reproducibly engrafts in NOD/scid mice after administration of 10×106 cells. Both an HLA-A0201-restricted H-Y-specific CD8+ CTL clone and the DRB30301-restricted H-Y-specific CD4+ helper T-cell clone that we earlier described were used to investigate the anti-leukemia efficacy of CD8+ and CD4+ T cells in NOD/scid mice. Results In vitro, the CD8+ H-Y specific CTL clone was highly cytotoxic against the ALL-CM leukemia. The H-Y specific CD4+ helper T-cell clone did not lyse the leukemia, but produced IFN-γ upon recognition. Infusion of the H-Y-specific CD8+ CTL clone (25×106 cells/mouse) 3 days after ALL-CM leukemia challenge significantly delayed leukemia progression by 3 weeks compared to a CMV-specific CD8+ CTL control clone (p<0,001). Despite no measurable in vitro cytotoxicity, the H-Y-specific CD4+ helper T-cell clone (25×106 cells/mouse) delayed leukemia progression by 2 weeks compared to a leukemia non-reactive HLA-DR1-specific CD4+ helper T-cell control clone (p<0,001). In vitro co-incubation of the H-Y-specific CD4+ helper T-cell clone did not influence leukemia proliferation but induced up-regulation of MHC-class I and II, CD80, CD86 and CD40. In vitro, pre-incubation of leukemia cells with the H-Y-specific CD4+ helper T-cell clone irradiated did not improve the in vivo anti-leukemia efficacy of the H-Y-specific CD8+ CTL clone. Co-infusion of the H-Y specific CD4+ helper T-cell clone did not augment the in vivo persistence of the H-Y-specific CD8+ CTL T-cell clone. Nevertheless, the co-infusion resulted in a delay in leukemia progression of approximately 5 weeks, suggesting an additive, non overlapping anti-leukemia mechanism. Conclusions Minor Hag-specific human CD4+ T lymphocytes may contribute to the GvL effect through a direct, non cytotoxic mechanism, which could be additive to that of CD8+ CTL. The nature of this non cytotoxic GvL effect is currently under investigation. A.B. and L.H. equally contributed to this study. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The interaction between CD8+ cytotoxic T cells and Leishmania-infected macrophages.

1991 ◽  
Vol 174 (3) ◽  
pp. 499-505 ◽  
Author(s):  
L E Smith ◽  
M Rodrigues ◽  
D G Russell
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Clone ◽  
Cytotoxic T Cells ◽  
T Cell Response ◽  
Cytotoxic T Cell ◽  
T Cell Clone ◽  
Vitro Model ◽  
Leishmania Parasites

Leishmania is resident within the macrophages of its vertebrate host. In any intramacrophage infection, where the pathogen is present in a form capable of mediating cell to cell transmission, the contribution of a cytotoxic T cell response to protective immunity is questionable. This study presents data from an in vitro model designed to elucidate the outcome of an interaction between CD8+, cytotoxic T cells and infected macrophages. Experiments were conducted with an H-2d-restricted, cytotoxic CD8+ T cell clone and Leishmania parasites present in mixed macrophage cultures, with the parasites confined to either histocompatible BALB/c macrophages, or incompatible CBA macrophages. Initial experiments indicated that the viability of Leishmania was unaffected by the lysis of its host macrophage by cytotoxic T cells. However, extended experiments showed that the parasites were killed between 24 and 72 h. The same results were obtained regardless of whether the parasites were resident in the target, BALB/c, macrophages or the bystander, CBA, macrophages. Addition of neutralizing, anti-IFN-g antibody to the cultures ablated most of the leishmanicidal behavior, indicating that parasite death was attributable to macrophage activation, resulting from cytokine secretion from the T cells following the initial recognition event.

scholarly journals Isolation of a T-Cell Clone Showing HLA-DRB1*0405-Restricted Cytotoxicity for Hematopoietic Cells in a Patient With Aplastic Anemia

Blood ◽  
1997 ◽  
Vol 89 (10) ◽  
pp. 3691-3699 ◽  
Author(s):  
Shinji Nakao ◽  
Akiyoshi Takami ◽  
Hideyuki Takamatsu ◽  
Weihua Zeng ◽  
Naomi Sugimori ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Aplastic Anemia ◽  
Mononuclear Cells ◽  
Cell Clone ◽  
Cytotoxic T Cells ◽  
Hematopoietic Cells ◽  
T Cell Clone ◽  
Cd34 Cells

Abstract The existence of T cells capable of inhibiting in vitro hematopoiesis has been shown in aplastic anemia (AA), although whether such inhibition is mediated by a specific immune reaction involving an HLA allele remained unknown. We isolated a CD4+ Vβ21+ T-cell clone that was most dominant among Vβ21+ T cells in the bone marrow (BM) of an AA patient whose HLA-DRB1 alleles included 1501 and 0405. The T-cell clone named NT4.2 lysed an autologous Epstein-Barr virus-transformed lymphoblastoid cell line (LCL) and phytohemagglutinin-stimulated lymphocytes (PHA-blasts) as well as allogeneic LCLs sharing HLA-DRB1*0405. Cytotoxicity against LCL cells and PHA-blasts by NT4.2 was blocked by anti–HLA-DR monoclonal antibody (MoAb) or anti-CD3 MoAb. NT4.2 also lysed autologous BM mononuclear cells enriched with CD34+ cells that had been cultured for one week in the presence of colony-stimulating factors as well as allogeneic CD34+ cells of a normal individual carrying HLA-DRB1*0405, cultured in the same way. Moreover, NT4.2 strongly inhibited colony formation by hematopoietic progenitor cells derived from cultured CD34+ cells sharing HLA-DRB1*0405. These results indicate that the AA patient has T cells capable of killing hematopoietic cells in an HLA-DRB1*0405-restricted manner and that such cytotoxic T cells may contribute to the pathogenesis of AA.

TIRC7 and HLA-DR axis contributes to inflammation in multiple sclerosis

2014 ◽  
Vol 20 (9) ◽  
pp. 1171-1181 ◽  
Author(s):  
JM Frischer ◽  
M Reindl ◽  
B Künz ◽  
T Berger ◽  
S Schmidt ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
T Cells ◽  
T Cell ◽  
Cell Clone ◽  
Ex Vivo ◽  
Peripheral Blood Lymphocytes ◽  
Cytokine Expression ◽  
Hla Dr ◽  
T Cell Clone

Background and objective: Interactions between TIRC7 (a novel seven-transmembrane receptor on activated lymphocytes) and its ligand HLA-DR might be involved in the inflammatory process in multiple sclerosis (MS). Methods: Methods comprised immunohistochemistry and microscopy on archival MS autopsies, proliferation-, cytokine-, and surface-staining assays using peripheral blood lymphocytes (PBLs) from MS patients and an in vitro model. Results: TIRC7 was expressed in brain-infiltrating lymphocytes and strongly correlated with disease activity in MS. TIRC7 expression was reduced in T cells and induced in B cells in PBLs obtained from MS patients. After ex vivo activation, T cell expression of TIRC7 was restored in patients with active MS disease. The interaction of TIRC7+ T lymphocytes with cells expressing HLA-DR on their surface led to T cell proliferation and activation whereas an anti-TIRC7 mAb preventing interactions with its ligand inhibited proliferation and Th1 and Th17 cytokine expression in T cells obtained from MS patients and in myelin basic protein-specific T cell clone. Conclusion: Our findings suggest that TIRC7 is involved in inflammation in MS and anti-TIRC7 mAb can prevent immune activation via selective inhibition of Th1- and Th17-associated cytokine expression. This targeting approach may become a novel treatment option for MS.

scholarly journals Mildly oxidized low-density lipoproteins suppress the proliferation of activated CD4+ T-lymphocytes and their interleukin 2 receptor expression in vitro

1998 ◽  
Vol 330 (2) ◽  
pp. 659-666 ◽  
Author(s):  
Sylvie CASPAR-BAUGUIL ◽  
Majed SAADAWI ◽  
Anne NEGRE-SALVAYRE ◽  
Mogens THOMSEN ◽  
Robert SALVAYRE ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cell Clone ◽  
Peripheral Blood Lymphocytes ◽  
Cd4 T Cell ◽  
Activated T Cells ◽  
T Cell Clone ◽  
Activated T Lymphocytes

Activated T-lymphocytes are present in early atherosclerotic lesions where they may interact with oxidized low-density lipoproteins (oxLDLs). In this study the non-specific effect of oxLDLs on the activation of T-cells in vitro was investigated. LDLs were oxidized by UV irradiation and characterized by a low level of lipid peroxidation and only slight apolipoprotein B modification. Peripheral blood lymphocytes from normal individuals were stimulated in vitro with the polyclonal activator phytohaemagglutinin in the presence of various doses of LDLs and oxLDLs. LDLs enhanced the proliferation of peripheral blood lymphocytes at doses up to 100 μg/ml but were inhibitory at 200 μg/ml, whereas low doses of oxLDLs (over 10 μg/ml) inhibited the proliferation. OxLDLs also inhibited the proliferative responses of an alloreactive CD4+ T-cell line immortalized by Herpes virus saimiri and an influenza haemagglutinin-specific CD4+ T-cell clone. Viability tests using Trypan Blue exclusion or expression of Apo2.7, an apoptosis marker, did not indicate any significant cell death at doses up to 100 μg/ml oxLDL. At this concentration, cell-cycle analysis showed an accumulation of cells at the G1/S interface in the CD4+ cell clone, without significant DNA fragmentation. The expression of the activation antigen CD25 on T-lymphocytes (on phytohaemagglutinin-activated T-cells and on CD4+ T-cell clone), requisite to the commitment of activated T-cells from G1 phase to S phase, was also inhibited by oxLDLs whereas expression of other activation antigens such as CD69 and HLA-DR was unchanged. In conclusion, these data show that mildly oxidized LDLs inhibit the proliferation and CD25 expression of activated T-lymphocytes and suggest that oxLDLs may slow down the T-cell response in atherosclerotic lesions.

scholarly journals Differential requirements of B cells from normal and allergic subjects for the induction of IgE synthesis by an alloreactive T cell clone.

1985 ◽  
Vol 162 (1) ◽  
pp. 202-214 ◽  
Author(s):  
D T Umetsu ◽  
D Y Leung ◽  
R Siraganian ◽  
H H Jabara ◽  
R S Geha
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Cell Clone ◽  
T Cell Clones ◽  
Igg Synthesis ◽  
Cell Clones ◽  
T Cell Clone ◽  
Ige Synthesis ◽  
Alloreactive T Cell

Human T cell helper/inducer clones were used to induce IgE synthesis in B cells from both allergic and nonallergic donors. An alloreactive T cell clone, activated by recognition of specific HLA-DR antigens, stimulated peripheral blood B cells from both allergic and nonallergic donors to synthesize IgE antibody. B cells of allergic donors differed from those of nonallergic donors in their requirements for induction of IgE synthesis. Induction of IgE synthesis in B cells from nonallergic individuals occurred only under conditions of cognate interaction, in which the B cells expressed the alloantigen recognized by the T cells. In contrast, IgE synthesis in B cells from allergic donors occurred under conditions of cognate interaction with T cells as well as bystander conditions where the B cells did not express the alloantigen recognized by the T cell clones and where the T cell clones were stimulated by third-party monocytes bearing the relevant alloantigens. Furthermore, bystander stimulation of IgE synthesis in allergic donors occurred in the presence of tetanus toxoid (TT) antigen-specific T cell clones activated by the appropriate TT-pulsed monocytes. In contrast to the differing requirements of B cells from normal vs. allergic subjects for the induction of IgE synthesis, these B cells did not differ in their requirements for the induction of IgG synthesis. IgG synthesis was induced in all B cells under conditions of cognate interaction with the T cells as well as under conditions of bystander stimulation. These results suggest that cognate T-B cell interactions may be important in the development of IgE immune responses in the normal host.

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