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D Kabelitz

Publications and source records attributed to D Kabelitz.

At least 19 recordsLinked to original sources
PubMed2006

An optimized method for the functional analysis of human regulatory T cells.

Naturally occurring regulatory T cells (Treg) suppress the activation of antigen-responsive T cells in a cell contact-dependent manner. In order to investigate the impact of soluble mediators and receptor-ligand interactions on the interplay between naive T cells and Treg, a reproducible suppressor cell assay which functions in the absence of additional feeder cells or antigen-presenting cells is mandatory. Here, we describe such a method which is suited to study the modulation of responder T cell/Treg interactions in vitro. Treg were isolated from negatively purified total human CD4+ T cells by positive selection using anti-CD25 monoclonal antibody (MoAb)-coated Dynabeads followed by a detachment step. The remaining CD4+ CD25- responder T cells were cocultured with CD4+ CD25+ Treg in the presence of T-cell Activation/Expansion Beads from Miltenyi Biotec pre-coated with anti-CD3 plus anti-CD28 monoclonal antibody (MoAb). The optimal concentration for coating was 5 microg/ml for both MoAb. At this concentration, strong proliferation of responder T cells was elicited which was almost completely suppressed by Treg at 1:1 cell ratios. When higher concentrations of anti-CD3/anti-CD28 MoAb were used for coating, Treg also showed some degree of proliferation. The optimized suppressor assay proved to be highly reproducible and was used here to confirm the partial or complete reversal of Treg-mediated T-cell suppression by some cytokines (IL-2, IL-15), soluble IL-6 receptor/IL-6 fusion protein and recombinant GITR-ligand. Furthermore, our data confirm that Treg do not need other cell types to suppress proliferation of CD4+ CD25- responder T cells.

Antibodies, Monoclonal↗
PubMed2005

Adverse effects of intradermal allogeneic lymphocyte immunotherapy: acute reactions and role of autoimmunity.

BACKGROUND: Immunotherapy with allogeneic lymphocytes was introduced as a therapeutic option for selected infertile couples in different centres worldwide 20 years ago. It has been suggested for other indications as well, e.g. for pregnant women at risk of a child with Rhesus-D haemolytic disease, or as a vaccine which might reduce the receptiveness for HIV-1 infection. Here we report on our experience on adverse side-effects of intradermal lymphocyte immunotherapy (LIT) for infertile couples using partner's lymphocytes. METHODS: Prospective 4 week follow-up of all couples from 2000 to 2003 for acute reactions (feedback 2687/3246 [corrected] 83%). All couples treated between 1996 and 2002 received questionnaires after 2-3 years (feedback 1914/3041, 63%). RESULTS: Local reactions predominantly consisted of redness and itching for approximately 2 weeks. Systemic reactions could be attributed to LIT in 6-8%. Blisters at the injection sites were characteristic of LIT but not dependent on the HLA class I mismatch status between cell donor and host. The incidence of autoimmune disease was 0.1%. Four patients developed thromboembolism in pregnancy which was not ascribed to antiphospholipid syndrome. CONCLUSIONS: Acute side-effects are comparable to those reported after intradermal vaccination for infectious diseases. Specific risks for anaphylaxis, autoimmune or graft versus host disease were not detected.

Adult↗
PubMed2005

Enhanced antimetastatic effect of fetal liver kinase 1 extracellular domain and interferon-gamma fusion gene-modified dendritic cell vaccination.

Antiangiogenic immunotherapy benefits from targeting antigens expressed on genetically stable endothelial cells and represents a novel modality for cancer treatment. Vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2, also known as flk1 in mouse) mediated VEGF signaling is the key rate-limiting step in angiogenesis. Blockade of the flk1 signaling pathway can significantly inhibit tumor cell-induced angiogenesis and lead to inhibition of tumor metastasis. Interferon-gamma (IFN-gamma) is a pleiotropic cytokine, which plays an important role in cell-mediated immunity. In this study, we tested the hypothesis that immunization of mice with soluble flk1 (sflk1) and IFN-gamma fusion gene-transfected dendritic cells (DC-sflk1-IFN-gamma) would induce a potent CTL response to flk1, leading to an inhibition of tumor-induced angiogenesis and metastasis. Our data show that immunization of mice with sflk1 gene-modified DC (DC-sflk1) could induce a CTL response to flk1, leading to profound inhibition of tumor-cell-induced angiogenesis and metastasis. However, more striking antimetastatic effects were achieved through induction of enhanced CTL response to flk1 and augmented inhibition of angiogenesis when mice were immunized with DC-sflk1-IFN-gamma. In vivo T-cell subset depletion experiments showed that CD8(+) T cells were mainly responsible for this antimetastatic effect. Our data extend the notion that DC-based active antiangiogenic immunotherapy is an effective modality for cancer treatment, and show that the antitumor efficacy of this strategy can be improved by combination with DC-based cytokine immunotherapy.

Animals↗
PubMed2005

The impact of electrical charge on the viability and physiology of dendritic cells.

The use of electrical charge for electroporation or electrofusion is widely applied to customize dendritic cells (DC) and their immunological properties as anticancer vaccines. The aim of this study was to evaluate the influence of various electrical field strengths on the recovery, viability and physiology of DC. Immature DC were transferred into low-conductive medium and electrically charged within a range of 0-1500 V/cm. Viability was assessed by Trypan Blue dye exclusion or staining with impermeant nucleic acid stains and fluorescence-activated cell sorter analysis. Additionally, apoptosis was determined by flow cytometry after staining with Annexin-V, endocytosis by uptake of fluorescein isothiocyanate-dextran and metabolic activity by a standardized fluorescent live/dead assay. There was a strong correlation between the electrical field strength and the viability and physiology of DC. Field strengths > or =1000 V/cm significantly impaired viability, metabolism and endocytotic activity. Dual fluorescence with 7-7-amino-actinomycin D and Annexin-V demonstrated that loss of viability was predominantly due to necrosis rather than apoptosis. Field strengths < or =500 V/cm allowed to maintain good cell viability and recovery of DC and did not cause alterations of metabolism and endocytosis. Therefore, the frequently used amplification of field strengths to improve the efficacy of electroporation and electrofusion requires critical re-evaluation.

Apoptosis↗
PubMed2004

Detection of the 4977 bp deletion of mitochondrial DNA in different human blood cells.

As recently reported, it is possible to detect and quantify the amount of the deleted human mitochondrial DNA (mtDNA) in whole blood, platelets and peripheral blood mononuclear cells using real-time PCR. The aim of this study was to identify the cell types in human blood carrying the 4977 bp deleted mtDNA and their accumulation with regard to donor age. Whole blood from 10 healthy donors (five individuals aged from 19 to 22 years, five aged from 57 to 61 years) was separated in various cell populations such as granulocytes, B cells/monocytes and T cells. Purity of the cell isolates was determined by flow cytometry. Total DNA was extracted and 250 ng DNA of each cell type was subjected to PCR using fluorescent-labelled primer pairs. The specific PCR product of the 4977 bp deletion was quantified using an automated detection system. The accumulation of the 4977 bp deletion was more pronounced in T lymphocytes and granulocytes in comparison to B lymphocytes/monocytes. The amount of the 4977 bp deletion in whole blood varied from 0 to 0.00018%, in T lymphocytes from 0.00009 to 0.00160%, in granulocytes from 0 to 0.00162% and in the B lymphocyte/monocyte fraction from 0 to 0.00025%. The higher amount of the deletion in T lymphocytes may be due to a subset of lymphocytes with a longer lifespan thus facilitating the accumulation of mitochondrial damage. The higher amount in granulocytes could have the explanation in the higher release of free radicals for prevention of infectious diseases, because free radicals are supposed to damage the macromolecules of this cell type. The 10 donors displayed differences in the pattern of the accumulation with regard to the different cell types, but no age-dependent accumulation was observed. Differences of the accumulation pattern may be due to actual individual living behaviour or environmental factors.

Adult↗
PubMed2004

Regulation of T-cell death-associated gene 51 (TDAG51) expression in human T-cells.

T-cell death-associated gene 51 (TDAG51) has been described to regulate T-cell receptor/CD3-dependent induction of CD95/Fas and subsequent activation-induced cell death (AICD) in a murine T-cell hybridoma. Using well-defined pharmacological inhibitors, we investigated the regulation of TDAG51 expression in human T-cells and the correlation with cell death. TDAG51 was induced in resting T-cells, lymphoid cell lines and AICD-susceptible as well as AICD-resistant T-cell clones, and induction was inhibited by MAP-kinase inhibitors and PKC inhibitor Gö6983. No correlation between the effects of inhibitors on TDAG51 expression and cell death was observed. The constitutive TDAG51 expression in five pancreatic carcinoma cell lines was reduced by MAP-kinase inhibitors but not by Gö6983. Furthermore, the inducible overexpression of TDAG51 in TetOn Jurkat cells did not modulate cellular proliferation, phorbolester/ionomycin-induced growth arrest, or the expression of various cell surface molecules. Our results indicate that the expression of TDAG51 in human T-cells does not correlate with AICD.

Apoptosis↗
PubMed2003

CD95 ligand--death factor and costimulatory molecule?

The CD95 ligand is involved as a death factor in the regulation of activation-induced cell death, establishment of immune privilege and tumor cell survival. In addition, CD95L may serve as a costimulatory molecule for T-cell activation. Alterations in expression or shedding of membrane and soluble CD95L are associated with numerous diseases, and underscore the pathophysiological relevance of the CD95/CD95L system. In most cases, the causal link between altered CD95L expression and pathophysiology is unknown. Given the potency of the molecule to regulate death and survival of many different cell types, the control of CD95L production, transport, storage, shedding and inactivation is of tremendous biological and clinical interest. This review summarizes the current knowledge, hypotheses and controversies about CD95L as a multifunctional ligand and receptor. It considers the different roles of membrane and soluble forms of CD95L and the complex networks of intracellular dynamics of protein trafficking, as well as the potential bidirectional signal transduction capacity of CD95L, with a focus on molecular interactions that have been worked out over the past years.

Animals↗
PubMed2003

Why not work on T and NK cells in the Kunkel laboratory?

Coming from Hans Wigzell's laboratory in Uppsala, Sweden, I joined the Kunkel laboratory in 1981 to spend a post-doctoral fellowship period financed by the German Research Organization. While I initially worked with Nick Chiorazzi in an attempt to generate monoclonal antibody-secreting human B-cell hybridomas, I later studied the in vitro effects of tumor promoters on human natural killer cells and collaborated with Mary Crow on some aspects of the so-called autologous mixed lymphocyte reaction. Working in the stimulating atmosphere of the Kunkel laboratory was an exceptional experience. I was particularly impressed by the efficient organization of clinical research at Rockefeller University. The following is a very personal resumee of my stay in the Kunkel laboratory.

Allergy and Immunology↗
PubMed2001

Multiple interactions of the cytosolic polyproline region of the CD95 ligand: hints for the reverse signal transduction capacity of a death factor.

The CD95/Fas/Apo-1 ligand is expressed on activated lymphocytes, NK cells, platelets, certain immune-privileged cells and some tumor cells and induces apoptosis through the death receptor CD95/Fas/Apo-1. In murine T cells, membrane-bound CD95L (Fas ligand) also acts as a costimulatory receptor to coordinate activation and function in vivo. The molecular basis for this reverse signal transduction is yet unknown. In the present report, we identify individual interaction domains of enzymes and adapter molecules that selectively interact with full-length CD95L from transfectants and human T cells. These results may help to explain the costimulatory capacity of CD95L.

Amino Acid Sequence↗
PubMed2001

[Immune deficiency].

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Adjuvants, Immunologic↗
PubMed2001

Differentiation of resting human peripheral blood gamma delta T cells toward Th1- or Th2-phenotype.

Depending on the microenvironment, murine gamma delta T cells differentiate into either Th1 (IFN-gamma-producing) or Th2 (IL-4-producing) cells. It is unclear, however, whether circulating human peripheral blood gamma delta T cells can be driven into Th1 or Th2 cells by modulation of the priming cytokine milieu. In this study, peripheral blood gamma delta T cells were stimulated by phosphoantigen (isopentenyl pyrophosphate) or Daudi lymphoma cells in the presence of Th1-priming (rIL-12, anti-IL-4 Ab) or Th2-priming (rIL-4, anti-IL-12 Ab) conditions. Single-cell analysis of cytokine secretion (IFN-gamma and IL-4) was performed by flow cytometry after 18 h and after restimulation of expanded gamma delta T cells. The early activation of resting gamma delta T cells was characterized by the induction of IFN-gamma. Priming under Th1 conditions induced a Th1 profile characterized by increased secretion of IFN-gamma and TNF-alpha, while Th2 conditions caused increased production of IL-4 (Th2 profile) by the gamma delta T cells. These results indicate that the major subset of human gamma delta T cells can be polarized into either Th1 or Th2 cytokine pattern depending on the cytokine milieu in which contact with antigen occurs.

Antibodies, Monoclonal↗
PubMed2001

Role of gamma delta T-lymphocytes in HIV infection.

T-lymphocytes expressing the gamma delta T-cell receptor (TCR) comprise a small proportion (1-5%) of circulating CD3(+) T-lymphocytes. While T-cells expressing a V delta 2V gamma 9-encoded TCR dominate among peripheral blood gamma delta T-lymphocytes in healthy individuals, significant alterations in the gamma delta TCR repertoire are observed in HIV-infected persons. These changes are due to the selective preservation (and frequently moderate expansion) of V delta 1-expressing cells and the simultaneous depletion of V delta 2-expressing cells. In this brief review, we discuss the alterations in the gamma delta T-lymphocyte compartment in HIV infection, with special emphasis on the potential role of gamma delta T-cell in the immune defense against HIV.

HIV Infections↗