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Biomedical subjects

W Holter

Publications and source records attributed to W Holter.

At least 37 records · Page 2Linked to original sources
PubMed1996

Enhanced production of IL4 but not of IFN gamma and IL 10 by peripheral blood mononuclear cells from atopic children in response to CD2 plus CD28 stimulation.

Peripheral blood mononuclear cells from 16 children with atopic disease (range of IgE levels: 33 - 2892 kU/l) and 12 age matched controls were stimulated either with mAbs specific for CD3, CD2, CD3 plus CD28, CD2 plus CD28, with Tetanus Toxoid, SEA, or PHA plus PMA and their cell proliferation was determined. In addition, their cytokine production (IL2, IL4, IL10, IFN gamma) following selected stimuli was measured. We found that the cells from atopics proliferated significantly better in response to CD2 stimulation than control cells, with no difference in response to CD3 or SEA stimulation. Furthermore, cells from atopics produced significantly higher amounts of IL4 than cells from controls, a difference most pronounced following CD2 plus CD28 stimulation. No differential production was found for IL10 and IFN gamma. We conclude that in atopic children with moderately elevated IgE a hyperreactivity of the CD2 pathway of stimulation and a clear elevation of IL4 but not of IL10 or IFN gamma production can be demonstrated.

Adolescent↗
PubMed1995

Role of accessory cells in cytokine production by T cells in chronic B-cell lymphocytic leukemia.

We investigated the production of cytokines by highly purified T helper cells from B-cell chronic lymphocytic leukemia (B-CLL) patients stimulated by different activation pathways, and we studied the influence of various accessory cell populations on the pattern of the secretion of cytokines, including interleukin (IL)-2, IL-4, interferon-gamma (IFN-gamma), and IL-10. Neither a qualitative nor a quantitative difference in cytokine production and proliferative capacity was observed in CLL-derived purified T cells compared with normal individuals, when T cells were stimulated by different pathways, including CD3, CD2, and costimulation with CD28. Addition of autologous accessory cells (aAC), however, dramatically influenced the cytokine pattern of normal versus B-CLL-derived T cells. CLL cells as aAC caused a marked increase of IL-2, whereas IFN-gamma was only slightly induced and IL-4 was not influenced. In contrast, in normal individuals addition of aAC, which predominantly consisted of monocytes, resulted in a significant increase of IFN-gamma and a reduction of IL-4 secretion. IL-2 production was inhibited by higher concentrations of aAC. The increased stimulation of IL-2 production by CLL cells was not specific to the leukemic cell population, as purified B cells from normal individuals had the same effect. On the other hand, purified monocytes from CLL patients and controls both induced IFN-gamma production and inhibited IL-4 secretion. After antigen-specific stimulation with tetanus toxoid, cytokine secretion was influenced by the type of aAC in a similar pattern. We conclude that T helper cells derived from patients with B-CLL are intrinsically normal and that the predominance of B cells as accessory cells in CLL significantly alters the immune function of T helper cells in vitro.

Antigen-Presenting Cells↗
PubMed1995

Identification of the TS2/18-recognized epitope on the CD2 molecule as a target for suppression of T cell cytokine synthesis.

CD2 mAb can inhibit T cell activation, but the mechanisms involved are still unclear. In this study, we identify the mAb TS2/18, previously reported to bind to an epitope on the distal domain of the CD2 molecule at amino acids 87-99 (1), as a particularly potent inhibitor of T cell cytokine synthesis. Although TS2/18 is comitogenic with the CD2R mAb VIT13, this mAb combination does not induce the secretion of substantial amounts of cytokines. When added to T cells stimulated with the CD2 mAb pair OKT11-VIT13, TS2/18 efficiently blocks the induction of cytokine synthesis induced by that CD2 mAb pair, although it does not interfere with the binding of OKT11. In addition, TS2/18 inhibits the increase in protein tyrosine phosphorylation and the accumulation of phosphatidic acid induced by either OKT11-VIT13 or a cross-linked CD3 mAb. Finally, TS2/18 disrupts CD2 clusters induced by the CD2 mAb pair OKT11-VIT13. We conclude that TS2/18 blocks T cell cytokine synthesis by interfering with early signal transduction, possibly by impairing the formation of signal-transducing molecule complexes on the T cell surface. Together, these data identify the CD2 epitope recognized by the mAb TS2/18 as a candidate epitope for T cell-specific immunosuppressive ligands.

Antibodies, Monoclonal↗
PubMed1995

Crosslinking of CD27 in the presence of CD28 costimulation results in T cell proliferation and cytokine production.

Monoclonal antibodies recognizing CD27, a member of the nerve growth factor receptor family, have been observed to enhance or inhibit PHA- or CD3 mAb-stimulated T cell proliferation. In this study, we investigate the effects of CD27 stimulation on the proliferation and cytokine production of T cells stimulated simultaneously through CD3, CD2, or CD28. Here we report that simultaneous crosslinking of CD27 plus CD28 results in T cell proliferation and in the production of IL-2, IL-4, IL-10, and IFN-gamma. CD27 plus CD28 stimulation thus introduces a novel Ag-independent pathway of T cell activation. We further show that all major T cell subsets (CD4+, CD8+, CD4+CD45RA+, or CD4+CD45RO+ T cells) respond to CD27 plus CD28-mediated costimulation. Synergistic effects on T cell stimulation are also found when CD27 is crosslinked on cells stimulated simultaneously through CD3 or CD2. In further experiments we show that crosslinking of CD27 elevates cytoplasmic free Ca2+ levels. Finally, both the CD3 plus CD27 and the CD28 plus CD27-stimulated T cell proliferation is sensitive to inhibition by CsA. Taken together, these data emphasize the importance of CD27 stimulation in the context of simultaneously received signals through CD3, CD2 or, most importantly, through CD28. Furthermore, signaling through CD27 appears to involve Ca(2+)-dependent mechanisms sensitive to CsA.

Antibodies, Monoclonal↗
PubMed1995

High IL-4 production is a stable phenotype of CD8negCD45RAnegCD27neg T cells.

CD27neg T cells are found only among CD4pos-CD45ROpos T cells and represent a T cell subset functionally distinct from CD27pos T cells. We examined CD4posCD45ROpos T cells that were sorted into CD27neg and CD27pos populations for their cytokine production in response to different activation pathways. We found that CD27neg T cells are characterized by high IL-4 and low IL-2 production, regardless of whether the cells were activated through CD3 plus CD28, CD2 plus CD28, or PHA plus PMA. However, subpopulation-specific patterns of cytokines were the clearest demonstrable following CD2 plus CD28 stimulation. We conclude from these data that high IL-4 production is a stable phenotype of CD27neg T cells.

Adult↗
PubMed1995

High-level IL-10 production by monoclonal antibody-stimulated human T cells.

We investigated interleukin-10 (IL-10) production in freshly isolated mononuclear cells and purified T cells in response to stimulation with monoclonal antibodies (mAb) recognizing CD3, CD2 and CD28, or with the bacterial products Staphylococcus aureus cells (SAC), staphylococcal enterotoxin (SEA) and lipopolysaccharide (LPS). IL-10 production was compared with that of IL-2, IL-4 and interferon-gamma (IFN-gamma). Similar to the other cytokines, in peripheral blood mononuclear cells (PBMC) from adult donors the highest IL-10 levels were produced in response to CD2 plus CD28 stimulation, within 72-96 hr of stimulation. Levels of IL-10 in response to CD2 plus CD28 stimulation (1.9 +/- 1 ng/ml) exceeded those in response to SEA (0.25 +/- 0.16 ng/ml), SAC (0.43 +/- 0.42 ng/ml), or LPS (0.19 +/- 0.14 ng/ml) stimulation. With adult purified T cells, high levels of IL-10 and IL-4 were measured following CD3 plus CD28 stimulation, and the amounts of both T-helper type-2 (Th2) cytokines decreased following the addition of phorbol myristate acetate (PMA), whereas the synthesis of the Th1 cytokines IL-2 and IFN-gamma was enhanced. When PBMC were stimulated with a CD3 mAb and different other cytokines were added, strong enhancement of IL-10 production was seen upon the addition of IL-2, IL-4, IL-7, IL-12 and IFN-gamma, whereas inhibition was found with transforming growth factor-beta 1 (TGF-beta 1). These data illustrate that in freshly isolated PBMC large amounts of IL-10 can be induced rapidly by appropriate mAb stimulation, and that even in freshly isolated cells IL-4 and IL-10 show signs of parallel regulation.

Antibodies, Monoclonal↗
PubMed1994

TGF-beta 1 is a potent inducer of human effector T cells.

TGF-beta 1 is known to modulate lymphocyte activation affecting cell proliferation and the production of cytokines and Igs. Little is known about the characteristics of T cells grown in the presence of TGF-beta 1. We have stimulated human T cells with PHA in the presence of TGF-beta 1 under serum-free conditions for 7 days and characterized the resulting cell population. TGF-beta 1 (0.0032 to 10 ng/ml) affected neither [3H]thymidine incorporation (day 4) nor cell yield (day 7) in these cultures. However, cells activated in the presence of TGF-beta 1 proliferated vigorously in secondary cultures and produced highly elevated amounts of IL-2 (12 +/- 3-fold enhancement of IL-2 production in response to CD2 plus CD28 stimulation compared with control cells, mean +/- SEM; n = 10). The enhancing effects of TGF-beta 1 were demonstrable over a wide range of concentrations (0.4 to 10 ng/ml). The increased IL-2 protein production was paralleled by a dramatic up-regulation of IL-2 mRNA. In addition, cells precultured with TGF-beta 1 responded with enhanced cluster formation in the secondary cultures. With regard to their phenotype, we observed an increased expression of the alpha E beta 7-integrin human mucosal lymphocyte-1 and of the CD2-restricted epitope CD2R, whereas the expression of CD11a was slightly decreased. In contrast, TGF-beta 1 did not influence the constitutive or activation-induced expression of CD4, CD8, CD45RA, CD45RO, CD25, CD71, CD54, CD58, CD59, and B7. We conclude that TGF-beta 1 supports the generation of human effector cells with a strongly enhanced capacity to respond to subsequent restimulation.

Antibodies, Monoclonal↗
PubMed1994

Induced gene expression of the hypusine-containing protein eukaryotic initiation factor 5A in activated human T lymphocytes.

The hypusine-containing protein eukaryotic initiation factor 5A (eIF-5A) is a cellular cofactor critically required for the function of the Rev transactivator protein of human immunodeficiency virus type 1 (HIV-1). eIF-5A localizes in the nuclear and cytoplasmic compartments of mammalian cells, suggesting possible activities on the level of regulated mRNA transport and/or protein translation. In this report we show that eIF-5A gene expression is constitutively low but inducible with T-lymphocyte-specific stimuli in human peripheral blood mononuclear cells (PBMCs) of healthy individuals. In contrast, eIF-5A is constitutively expressed at high levels in human cell lines as well as in various human organs. Comparison of eIF-5A levels in the PBMCs of uninfected and HIV-1-infected donors shows a significant upregulation of eIF-5A gene expression in the PBMCs of HIV-1 patients, compatible with a possible role of eIF-5A in HIV-1 replication during T-cell activation.

Base Sequence↗
PubMed1994

Specific down-regulation of proliferative T cell alloresponsiveness by interference with CD2/LFA-3 and LFA-1/ICAM-1 in vitro.

T cell activation requires Ag contact with the TCR in the presence of costimulatory signals provided by APCs. When Ag is presented without costimulation, T cells are functionally inactivated. Here we demonstrate that interference with distinct adhesion molecules during Ag contact using mAbs leads to Ag-specific functional inactivation of alloreactive T cells. We found that the presence of a mixture of mAbs specific for CD2, LFA-3, LFA-1 alpha- and beta-chain, and ICAM-1 during primary MLC leads to down-regulation of secondary proliferative responses to Ag from the donor used for priming. Cells from pretreated cultures proliferated well, however, when stimulated with Ag from third party donors, mitogens, or mitogenic CD3 mAb. Because specific reactivity could be restored by addition of IL-2 to restimulation cultures, altered secondary responsiveness appeared to be caused by anergy and not by elimination of specific clones. Furthermore, specific down-regulation of alloresponsiveness was prevented by addition of IL-2 to primary cultures in the presence of mAb. Interference by mAb with either CD2/LFA-3, LFA-1/ICAM-1, CD2/LFA-1, or LFA-3/ICAM-1 had a substantial, though less pronounced effect on secondary responsiveness. After pretreatment with the Ab mixture, CTL generation was substantially but incompletely down-regulated against the original and third party donors. Because a decrease in the reactivity of unstimulated responders by culture was also observed, these findings might be explained by the loss of cytotoxic precursors after culturing under nonstimulating conditions. In conclusion, our data demonstrate that T cells enter a state of anergy when T cell activation is modulated by simultaneous interference with distinct adhesion molecules during Ag contact, which thus might reflect at least partly overlapping functions of particular receptor-ligand pairs in T cell costimulation.

Antibodies, Monoclonal↗
PubMed1994

Familial hemophagocytic lymphohistiocytosis associated with disseminated T-cell lymphoma: a report of two siblings.

Two siblings with evidence of disseminated T-cell lymphoma at the time of diagnosis of familial hemophagocytic lymphohistiocytosis (FHL) are reported, an association which has not been described previously. The first child with typical clinical and laboratory features of FHL died shortly after admission, before diagnosis could be established. Retrospective analysis of autoptic tissue revealed marked hemophagocytosis as well as morphological and immunohistochemical features suggestive of disseminated T-cell lymphoma. In the second child, FHL was diagnosed in time. Subsequent histologic investigation of bone marrow biopsies displayed a focal infiltration by T-cell lymphoma. DNA hybridization studies provided evidence of a monoclonal T-cell receptor beta chain gene rearrangement. Following conventional chemotherapeutic induction for FHL, the patient received an allogeneic bone marrow transplant (BMT) from a related healthy donor. Currently, 17 months after BMT, the boy is in unmaintained remission from FHL and T-cell lymphoma. The current pathogenetic concepts for FHL and a possible relationship between T-cell lymphoma and FHL are discussed.

Blotting, Southern↗
PubMed1994

Transforming growth factor-beta inhibits IL-4 and IFN-gamma production by stimulated human T cells.

The present study investigates the effect of transforming growth factor (TGF)-beta on the production of IL-4 and IFN-gamma by the leukemia Th0 type cell line HUT78, by freshly isolated human T cells, and by antigen specific human T cell clones. We found that IL-4 and IFN-gamma, but not IL-2, production by stimulated HUT78 cells was inhibited by TGF-beta 1. TGF-beta 1 also reduced the accumulation of IL-4 and IFN-gamma specific mRNA in stimulated HUT78 cells. However, IL-2 and IL-7 co-stimulated IL-4 and IFN-gamma production, whereas IL-1, IL-3, IL-5, IL-6, IL-8, tumor necrosis factor-alpha or granulocyte macrophage colony stimulating factor had no effect. Because IL-2 is an important helper cytokine for the production of IL-4 and IFN-gamma, we investigated whether signal transduction through the IL-2 receptor is impaired by TGF-beta 1. We found that tyrosine phosphorylation in response to IL-2 in HUT78 cells was strongly inhibited by a short preincubation with TGF-beta 1. Evidence for an antagonistic role for TGF-beta 1 and IL-2 comes from the finding that high doses of IL-2 could partially overcome TGF-beta 1 mediated inhibition of IL-4 and IFN-gamma production. Similar to its effect on HUT78 cells, TGF-beta 1 also inhibited IL-4 and IFN-gamma production by freshly isolated T cells as well as by human T cell clones. Taken together, our experiments show that the IL-2 dependent cytokines IL-4 and IFN-gamma are both negatively controlled by TGF-beta under conditions where IL-2 production is unaffected by a mechanism which partially involves an inhibition of IL-2/IL-2R signal transduction. These data identify TGF-beta and IL-2 as mutual antagonists in the regulation of IL-4 and IFN-gamma production.

Blotting, Northern↗
PubMed1994

Retrobulbar T cells from patients with Graves' ophthalmopathy are CD8+ and specifically recognize autologous fibroblasts.

Graves' ophthalmopathy is an autoimmune condition characterized by T cell infiltration of the retrobulbar tissue. Phenotypic and functional analysis of these infiltrating cells may provide insight into the pathogenesis of the disease. IL-2-responsive cells were therefore grown out of the retrobulbar tissue from two patients with severe Graves' ophthalmopathy undergoing orbital decompression surgery, and six T cell lines were established and characterized. They consisted predominantly of CD8 + CD45RO+ cells and secreted IL-4, IFN-gamma, and IL-10 upon activation. When screened for their antigen reactivity, all lines proliferated in response to stimulation with autologous retrobulbar fibroblasts in an HLA class I-restricted manner, but did not recognize autologous peripheral blood mononuclear cells, crude eye muscle extract, allogeneic cells, or purified protein derivate of Mycobacterium tuberculosis. In contrast, PBMC from the same patients responded readily to purified protein derivate of Mycobacterium tuberculosis and allogeneic PBMC, but did not recognize autologous fibroblasts. Interestingly, only one of the six retrobulbar T cell lines displayed cytotoxicity towards its specific target cell population. These results suggest that the retrobulbar fibroblasts are a major T cell target in Graves' ophthalmopathy. Pronounced cytokine production in the absence of target cell cytotoxicity may explain fibroblast proliferation, glycosaminoglycan secretion, and secondary eye muscle enlargement in this condition.

Adult↗
PubMed1993

The soluble pool of beta 2-microglobulin free HLA class I alpha-chains. Qualitative and quantitative characterization.

Previous studies have demonstrated that HLA class I heterodimers are present in plasma and cell culture supernatants. They can be precipitated by mAb the binding of which is dependent on the proper association of the polymorphic alpha-chain with beta 2-microglobulin (beta 2-m). The molecular mass of the alpha-chain ranges from 45 to 35 kDa with a number of intermediate products. We report on the identification of 35-kDa soluble beta 2-m free HLA class I H chains immunoprecipitated by mAb LA45 from cell culture media of activated B and T cells. Furthermore, a peptide-based competitive immunosorbent assay was established to determine the amounts of soluble HLA class I alpha-chains. By means of this assay, we formally proved the specificity of mAb LA45 for a linear epitope on HLA class I H chains centered on residues arginine-asparagine at positions 62 and 63 of the alpha 1-domain. PHA or rIL-2 were identified as efficient stimuli for PBMC leading to the generation of soluble beta 2-m free HLA class I H chains. Testing of cell lines representing distinct stages of hematopoietic differentiation demonstrated a significant correlation between cell surface expression of beta 2-m free HLA class I H chains and amounts of soluble LA45 reactive molecules. However, three of six human T lymphotropic virus type I transfected cell lines, although expressing beta 2-m free H chains, do not generate soluble molecules. Finally, human sera were found to contain considerable amounts of beta 2-m free HLA class I H chains. The average amount of these molecules in sera of individuals with one positive LA45 allele was determined to be 46.9 +/- 38.6 nM/liter.

Amino Acid Sequence↗
PubMed1993

Suramin affects human peripheral blood mononuclear cells in vitro: inhibition of T cell growth and modulation of cytokine secretion.

Suramin, a polyanionic compound, which has been in clinical use for the treatment of African trypanosomiasis for several decades, has recently been introduced in clinical oncology. Its effects on the immune system seemed therefore of interest. In the present study we tried to elucidate in vitro how suramin affected different functions of human peripheral blood mononuclear cells (PBMC). Suramin suppressed the proliferation of PBMC in response to various stimuli, including OKT3, phytohemagglutinin (PHA), phorbolmyristate-acetate (PMA) and ionomycin, purified protein derivate of Mycobacterium tuberculosis (PPD) and antibodies against CD2. It also inhibited the binding of monoclonal antibodies to T cell surface antigens. This effect was not dependent on the isotype of the antibody, but seemed to be highly epitope-specific. Among a panel of antibodies against one antigen, only a few were affected by the compound. Whereas the binding of Leu3a and OKT3 was for instance fully suppressed by suramin, OKT4 and Leu4 binding was only slightly affected. Suramin also decreased the expression of T cell surface molecules such as CD2, CD25 and CD4 in preactivated PBMC and had pronounced effects on cytokine production. Interestingly the compound had adverse regulatory effects on different cytokines. Whereas the secretion of interferon-gamma was completely suppressed by suramin, interleukin-2 (IL-2) and IL-4 production was stimulated. These results demonstrate that suramin affects T cell function in multiple different ways. This will have to be considered, when suramin is used in the treatment of cancer patients.

Adult↗
PubMed1993

[Regulation of cytokine production by human T-lymphocytes in allergic immune response].

A network of cytokines regulates the growth and function of the cells of the immune system. T cells possess a dominant role in this network since they are the main source of many cytokines. The production of different cytokines is specifically regulated by means of cell interactions and cytokines and depends largely on the state of differentiation of the T cell. The production of certain cytokines is, therefore, restricted to defined subpopulations of T cells. IL2, IL4, IL5, IL10, IL12 and Interferon gamma (IFN gamma) play a central role in allergic immune response. The production of these cytokines can be restricted to specialized T cells. Two different types of differentiated T cells can be characterised according to the pattern of cytokine production of T cells: IL2 and IFN gamma are typically produced by T helper 1 (Th 1) cells, whereas predominantly T helper 2 (Th 2) cells produce IL4, IL5 and IL10. The selective activation of either Th 1 or Th 2 type cells depends on the antigen and is influenced by cytokines produced partly by antigen-presenting cells and partly by T helper cells. Typically, allergens induce an immune response which is dominated by Th 2 cells. These cells then stimulate the production of IgE by B cells.

Adult↗
PubMed1993

Interleukin-4 production by the malignant cell line HUT78.

Interleukin-4 (IL-4) is a cytokine difficult to induce in large quantities in freshly isolated cells. No malignant cell line has been described to date to produce IL-4 either constitutively or following activation. Here we report that HUT78 cells can be induced to produce IL-4 either by CD3 stimulation under cross-linking conditions or by soluble CD3 mAbs in the presence of PMA. IL-4-specific mRNA could be demonstrated readily under such conditions. Using this experimental model we investigated the role of IL-2 for IL-4 production. The addition of IL-2 strongly costimulated CD3-induced IL-4 production, whereas blockade of the IL-2/IL-2R pathway reduced IL-4 production by approximately 50%. IL-2 alone, however, could not induce IL-4 production. These results indicate that IL-2 is a helper of cytokine necessary, but not sufficient, for IL-4 production in HUT78 cells.

Antibodies, Monoclonal↗