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Biomedical subjects

S Miescher

Publications and source records attributed to S Miescher.

At least 37 records · Page 2Linked to original sources
PubMed1994

Neuropeptides are potent modulators of human in vitro immunoglobulin E synthesis.

We determined the effect of adrenocorticotropin hormone (ACTH) on the regulation of IgE synthesis. Depending on the concentration, ACTH enhanced or inhibited IgE synthesis in a culture system where IgE synthesis was induced with interleukin-4 (IL-4) and anti-CD40 monoclonal antibody in peripheral blood mononuclear cells. Similar effects on IgE synthesis were observed by adding ACTH-related peptides, e.g. corticotropin-releasing factor (CRF), the inducer of ACTH, or alpha-melanocyte stimulating hormone (alpha-MSH), a cleavage product of ACTH. However, ACTH had no effect on IgG or IgM synthesis in this culture system. ACTH did not act directly on either B or T cells as there was no influence on IgE synthesis in a system using purified B cells alone or co-cultured with T cells. The effect of ACTH on IgE synthesis was mediated by accessory cells. This was shown by priming purified CD14-positive monocytes with ACTH and reconstitution experiments. Therefore, these findings suggest that ACTH and the related peptides CRF and alpha-MSH can influence the microenvironment modulating an IL-4 and anti-CD40 monoclonal antibody driven class switching to IgE via accessory cells.

Adrenocorticotropic Hormone↗
PubMed1994

Inhibition of human IgE synthesis by anti-IgE antibodies requires divalent recognition.

We used a selection of well-characterized murine monoclonal anti-IgE antibodies to investigate their effect on human in vitro IgE synthesis. We found anti-IgE antibodies that either inhibited or enhanced interleukin-4 plus anti-CD40-induced in vitro IgE synthesis in peripheral blood mononuclear cells (PBMC). This differential activity was isotype specific as neither IgM nor IgG synthesis were affected. Interestingly, only coding IgE mRNA was down-regulated, whereas germ-line epsilon RNA expression was not influenced by anti-IgE monoclonal antibody (mAb). On purified B cells all anti-IgE mAb inhibited interleukin-4 plus anti-CD40-induced IgE synthesis, implying a role of non-B cells for the enhancing activity observed in PBMC. Using Fab and F(ab')2 of an inhibitory anti-IgE mAb we could show that divalent recognition was required for inhibition of IgE synthesis.

Antibodies, Anti-Idiotypic↗
PubMed1994

Domain-specific anti-IgE antibodies interfere with IgE binding to Fc epsilon RII.

Human anti-IgE autoantibodies have been identified and implicated in the regulation of IgE-mediated reactions and IgE synthesis. In order to study the potential regulatory role of anti-IgE antibodies on IgE binding to the Fc epsilon RII we used a panel of IgE-specific monoclonal antibodies that were mapped by Western blotting against a series of recombinant epsilon domain peptides. Antibodies specific for all epsilon domains were detected except those against C epsilon H1. Using a competitive inhibition cell-binding assay on Fc epsilon RII + 8866 cells, we identified two major patterns of anti-IgE activity. Antibodies specific for the C epsilon H3 domain removed IgE whereas those specific for the C epsilon H2 domain enhanced IgE binding to the Fc epsilon RII. The anti-C epsilon H2 antibodies, in contrast to the anti-C epsilon H3 antibodies, could not dissociate cell-bound IgE from the Fc epsilon RII. Using preformed immune complexes of IgE and anti-IgE antibodies, it was clear that the anti-C epsilon H2 antibodies bound more IgE to the Fc epsilon RII by addition of immune complexes to the cell surface. Our results suggest that the opposing actions of either inhibition or enhancement of IgE binding by anti-IgE antibodies are related to their epsilon domain specificity.

Animals↗
PubMed1993

A specific feedback by anti-IgE autoantibodies on the cytokine network in allergy.

During recent years we have shown that anti-IgE antibodies can have different biological functions. Depending on their epitope specificity they can be anaphylactogenic or not, they interfere with IgE binding to its receptor or not, and they enhance or inhibit IgE synthesis. Therefore we propose a theoretical model implying that anti-IgE autoantibodies are specific feed back molecules that neutralize IgE induced by the cytokine network. In the normal individual this system would be beneficial, where as the atopic individual, due to differences in its B cell repertoire, will produce the wrong type of anti-IgE antibody. The wrong type of anti-IgE antibody may even aggravate the disease as some of these autoantibodies may induce IgE synthesis or trigger effector cells that in turn generate a Th2 like cytokine pattern.

Antibody Specificity↗
PubMed1993

Biological activities of anti-IgE antibodies.

Naturally occurring anti-IgE autoantibodies represent a heterogeneous mixture of antibodies with diverse specificities and biological functions. By using murine monoclonal anti-IgE autoantibodies directed against different epitopes on the IgE molecule as a model for autoantibodies, we could show that only a minority of antibodies combine all beneficial biological activities, such as the activity of inhibiting in vitro IgE synthesis, removing IgE from the surface of CD23+ cells and not being anaphylactogenic. While it is difficult to isolate and measure anti-IgE antibodies in human serum, it is now possible to generate such human anti-IgE antibodies by the method of repertoire cloning. Thus, human recombinant antibodies against IgE may become available for the treatment of atopic disease.

Animals↗
PubMed1992

Production of tumor necrosis factor-alpha by naive or memory T lymphocytes activated via CD28.

While it is well established that activated T cells can produce tumor necrosis factor alpha (TNF-alpha), it is less clear whether this function is confined to a given subset, e.g., memory cells. To approach this question, we investigated the production of TNF-alpha by human peripheral blood T lymphocytes activated with anti-CD28 mAb since this activation pathway is known to potentiate cytokine production. Under the culture conditions used, the amount of TNF-alpha produced was markedly enhanced compared to that obtained after activation with immobilized anti-CD3 mAb. The enhancement of TNF-alpha production was already apparent after incubation of T cells for 6 hr. Up to 5 ng/ml of TNF-alpha was measured on Day 2 in supernatants of cultures of 10(4) T lymphocytes. To determine the source of the cells producing high amounts of TNF-alpha, T lymphocytes were separated into two subpopulations, namely naive cells (expressing the CD45RA isoform) and memory cells (expressing the CD45RO isoform). While both subpopulations proliferated equally well after stimulation with anti-CD28 mAb, up to 90% of the TNF-alpha produced under these conditions originated from memory T cells. These results thus document that T cell activation via CD28 results in a marked increase in TNF-alpha production without affecting the functional disparity that exists between naive and memory T cells.

Antibodies, Monoclonal↗
PubMed1991

Cytotoxic potential despite impaired activation pathways in T lymphocytes infiltrating nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is an epithelial tumor consistently associated with EBV. The histological picture is characterized by a strikingly abundant lymphocytic infiltrate. Furthermore, the epithelial tumor cells present several immunological characteristics which suggest an important role for tumor-infiltrating lymphocytes (TIL) in the biology of this tumor. The present study reports the phenotypic and functional characterization of TIL from NPC obtained after enzymatic digestion of 15 NPC biopsies. Flow cytometric analysis of TIL suspensions indicated that most TIL were mature CD3+ T lymphocytes (mean = 60%) with a variable CD4/CD8 ratio. Most TIL were TCR alpha/beta-positive (mean = 55%) and only a few TCR gamma-delta-positive cells could be identified. A small percentage (mean = 9%) displayed an activated phenotype (CD25+, HLA class II+). Using limiting dilution analysis, we found that the average frequency of proliferative T-lymphocyte precursors (PTL-P) is lower among TIL (1/40) than in autologous (1/7) or normal PBL (1/1.4). Moreover, sorting experiments have shown that this defect is significantly more pronounced in the CD8+ than in the CD4+ TIL subset. Accordingly, the TCR and the CD2-mediated antigen-independent pathways of activation were impaired. Different types of cytotoxic precursor could be detected. These included lectin-dependent cell cytotoxicity (LDCC) and NK-like or lymphokine-activated killer (LAK) activity. Interestingly, some TIL from NPC were able to lyse an NPC tumor (C15) maintained in nude mice. Thus, despite impaired activation pathways, the cytolytic potential of proliferating TIL in NPC is preserved.

Adolescent↗
PubMed1991

IgG anti-IgE autoantibodies in immunoregulation.

Human sera contain anti-IgE autoantibodies with diverse biological functions in vitro. Opposite functions can be shown for triggering of IgE-mediated histamine release from human basophils in terms of anaphylactogenic or nonanaphylactogenic autoantibodies. Furthermore, autoantibodies are either capable of removing IgE from the surface of CD23-positive cells of binding more IgE to such cells. A similar dichotomy seems also to exist for the effect of autoantibodies on human IgE mRNA synthesis as well as IL-4-induced proliferation of human mononuclear cells. Thus, anti-IgE autoantibodies may represent a key factor in the manifestation and the development of allergic disease.

Antibodies, Anti-Idiotypic↗
PubMed1990

Sparse distribution of gamma/delta T lymphocytes around human epithelial tumors predominantly infiltrated by primed/memory T cells.

Evidence from the mouse system has suggested that T lymphocytes accumulating in non-lymphoid tissue, in particular epithelia, may preferentially express the T cell receptor (TCR) gamma delta. In this study, we characterize the T cell receptor alpha beta or gamma delta phenotype of lymphocytes infiltrating human tumors of epithelial origin using monoclonal antibodies (mAb) for immunohistology and flow cytometry on cells extracted by enzyme digestion. This report shows that the majority of CD3+ tumor-infiltrating lymphocytes are TCR alpha beta+ but a small percentage of TCR gamma delta can be clearly defined scattered throughout the tumor tissue with apparently no microanatomical selection. So far there has been little evidence for an accumulation of activated T cells in human tumor tissues as defined by mAb against molecules appearing transiently during the acute phase of activation. Now mAb are available that can identify primed or memory T cells such as mAb UCHL-1 recognizing the CD45RO antigen. Here we show that CD3+ tumor-infiltrating lymphocytes have a statistically significant accumulation of primed T cells, as compared to the autologous peripheral blood lymphocytes, suggesting their immune stimulation by tumor cells.

Adult↗
PubMed1990

Effect of transforming growth factor beta on the EL4 thymoma variant EL4/6.1: dissociation of inhibition of proliferation from expression of IL-1 and IL-2 receptors.

In order to further characterize the action of transforming growth factor beta (TGF-beta) on lymphoid cells, we investigated the effects of porcine TGF-beta 1 and -2 on the IL-1 sensitive EL4/6.1 thymoma cell line. The proliferation of EL4/6.1 thymoma cells was inhibited by TGF-beta 1 and TGF-beta 2 (1 ng/ml) to a similar degree, the population doubling time was increased by 50-60%, total inhibition was not achieved. This decrease of proliferation was associated with an increase of the number of cells in the G0/G1 compartment of the cell cycle. TGF-beta-mediated inhibition could not be overcome by adding exogenous rIL-1 nor was the binding capacity for IL-1 reduced. In addition, TGF-beta did not interfere with the induction of IL-2 receptors by a combination of Ionomycin+PMA+IL-1. The data suggest that TGF-beta mediated inhibition of thymocyte/lymphocyte proliferation is not associated with an inhibition of the expression or the induction of expression of IL-2 or IL-1 receptors.

Animals↗
PubMed1990

Stimulation of FACS-analysed CD4+ and CD8+ human tumour-infiltrating lymphocytes with ionomycin + phorbol-12,13-dibutyrate does not overcome their proliferative deficit.

Human tumour-infiltrating lymphocytes (TIL) were prepared by enzyme digestion from a series of different tumours and were purified on a fluorescence-activated cell sorter (FACS II) according to their CD4+ and CD8+ phenotype. CD4+ and CD8+ TIL were stimulated separately in a low density microculture system with phytohaemagglutinin (PHA) or with ionomycin plus phorbol-12, 13-dibutyrate (PDBu). The PHA-induced proliferation of TIL was highly decreased when compared with control peripheral blood lymphocytes. A decreased proliferation of TIL was also observed when cells were stimulated with ionomycin plus PDBu, a combination which is thought to circumvent early events associated with lymphocyte activation. Some TIL were also plated in limiting dilution where they showed decreased frequencies of proliferating T cell precursors. The data suggest that one component of the inhibition of TIL must be acting 'downstream' of the early events of lymphocyte activation.

CD4-Positive T-Lymphocytes↗
PubMed1989

Comparison of the immunosuppressive properties of milk growth factor and transforming growth factors beta 1 and beta 2.

The effects of the newly isolated bovine milk growth factor (MGF) which shows N-terminal homology to transforming growth factor beta 2 were compared with the effects of porcine transforming growth factor beta 1 and beta 2 (pTGF-beta 1 and -beta 2) on human T lymphocyte activation. Freshly isolated human PBMC were stimulated with either PHA, anti-CD3 + phorbol-12,13-dibutyrate (PDBu), or with a combination of ionomycin + PDBu. MGF, pTGF-beta 1, and pTGF-beta 2 decreased mitogen-induced [3H]thymidine incorporation by 30 to 75% in a dose-dependent manner. The maximum degree of inhibition was obtained at 1 ng/ml (40 pM) and could not be increased by increasing the concentration of teh transforming growth factor 10-fold. Stimulation of fresh T cells with the recall Ag tetanus toxoid was also inhibited (85%) by MGF at pM concentrations as was the proliferation of a human T cell clone specific for purified protein derivative. The effects of MGF and pTGF-beta 1 on anti-CD3-mediated increase of intracellular Ca2+ (Cai2+) was investigated by using the Fura-2 method. Neither MGF nor pTGF-beta 1 inhibited this increase in Cai2+ induced by a mitogenic concentration of anti-CD3 antibody. In order to determine whether TGF-beta preferentially inhibited the CD4+ or CD8+ subpopulation of human T cells, a limiting dilution analysis system, which allows every T cell to proliferate, was used. pTGF-beta 1 at a concentration of 5 ng/ml decreased the frequency of proliferating T cell precursors of both the CD4+ and CD8+ subsets to a similar extent. Furthermore, MGF, pTGF-beta 1, and pTGF-beta 2 also decreased IL-2 mediated [3H]thymidine incorporation into human PBL Con A blasts and the IL-4-mediated [3H]thymidine incorporation of purified T lymphocytes costimulated with PDBu by 70%. In conclusion, bovine MGF exerts suppressive effects on human T cells stimulated with Ag, mitogens, or interleukins, and the degree of T cell suppression is similar (or identical) to those of pTGF-beta 1 or -beta 2.

Animals↗
PubMed1989

Transforming growth factors beta 1 and beta 2 as well as milk growth factor decrease anti-CD3-induced proliferation of human lymphocytes without inhibiting the anti-CD3-mediated increase of [Ca2+]i and the activation of protein kinase C.

Porcine transforming growth factor 1 and 2 (pTGF-beta 1 and -beta 2) and milk growth factor (MGF) at 1 ng/ml significantly inhibited the proliferation of human lymphocytes induced by anti-CD3 antibodies. In contrast, the anti-CD3-mediated increase of intracellular Ca2+ and the activation and translocation of protein kinase C were not affected by the transforming growth factors.

Animals↗
PubMed1989

In vivo localization of a bispecific antibody which targets human T lymphocytes to lyse human colon cancer cells.

A bispecific MAb was derived from the fusion of a hybridoma producing MAb CD3 with a hybridoma producing MAb L-DI (which is directed against a 41-kDa glycoprotein expressed in most gastro-intestinal and pancreatic carcinomas). Bispecific antibody molecules were isolated from parental antibody molecules by the use of hydroxylapatite-HPLC and shown to target human cytolytic T lymphocytes, irrespective of their original specificity, to specifically lyse human colon carcinoma cells. Localization studies in vivo using nude mice bearing human colon carcinoma xenografts showed significant accumulation of the HPLC-purified 125I-labelled bispecific antibodies into the tumor compared to 131I-labelled control CD3 antibody.

Animals↗
PubMed1989

Transforming growth factors beta slow down cell-cycle progression in a murine interleukin-2 dependent T-cell line.

Transforming growth factors beta (TGF-beta) inhibit the growth of a variety of cell types, including lymphocytes. The immunosuppressive effects of TGF-beta have been attributed to the interference of these molecules with the interleukin-2 (IL-2)-driven component of lymphocyte proliferation. In order to elucidate in more detail the effects of TGF-beta on IL-2-induced proliferation, we investigated the effects of porcine transforming growth factor beta 1 and 2 (pTGF-beta 1 and 2) on the IL-2-driven proliferation of a murine IL-2-dependent T-lymphocyte line (CTLL). The results showed that pTGF-beta 1 and 2 decreased 3H-thymidine incorporation in CTLL cells in a dose-dependent fashion (maximum decrease of 75-85%). Combined-time kinetic analysis of the effects of pTGF-beta on 3H-thymidine incorporation, cell growth, and cell-cycle distribution (monitored as DNA content distribution) revealed that, in the first 48 h of culture, pTGF-beta 1 increased the doubling time from 11.4 to 19.2 h without significantly affecting the cell-cycle distribution of CTLL cells. After 96 h of culture in the presence of pTGF-beta 1, cells started to accumulate in G0/G1, although at this time point 30% of the pTGF-beta 1-treated cells were still in S-G2/M. Furthermore, during the first 48 h, neither the expression of the 55 kd chain of the IL-2 receptor (IL-2R) nor the expression of the transferrin receptor (TfR) was affected by TGF-beta. After 72 h of culture in the presence of pTGF-beta 1, the expression of the IL-2R and TfR was decreased. The data suggest that in CTLL cells TGF-beta initially slows the progression of cells in all phases of cell cycle. In addition, the initial TGF-beta-mediated decrease of IL-2-induced 3H-thymidine incorporation and cell proliferation in CTLL cells is not due primarily to downregulation of the IL-2R and/or TfR.

Animals↗
PubMed1988

Preferential clonogenic deficit of CD8-positive T-lymphocytes infiltrating human solid tumors.

The vast majority of tumor infiltrating lymphocytes (TIL) are either CD4+ or CD8+ T-lymphocytes. In order to examine directly the functional capabilities of the individual CD4+ and CD8+ TIL subsets we performed cell sorting of double immunofluorescence-labeled TIL recovered from 15 biopsies by enzyme digestion. These CD4+ and CD8+ TIL subsets were compared with similar subsets of T-lymphocytes from peripheral blood of normal subjects. Both CD4+ and CD8+ TIL showed a reduced clonogenicity as assessed quantitatively by limiting dilution analysis in a microculture system which allows every normal T-lymphocyte to undergo clonal expansion. The reduced clonogenic potential was unequally distributed among the CD4+ and CD8+ subsets with the CD8+ TIL showing a significant reduction of the frequency of proliferating T-lymphocyte precursors compared to the CD4+ TIL (with a median of 1/50 proliferating T-lymphocytes in CD8+ TIL versus a median of 1/11 in CD4+ TIL). The reduced response of CD8+ TIL was not caused by suppressor cells, lack of surface expression of CD2 and CD3 antigens nor of the alpha, beta T-cell receptor, nor by an accumulation of CD8+ cells of large granular lymphocyte morphology. Using low density cultures, the highly purified CD4+ and CD8+ TIL were stimulated either via the T-cell receptor or the CD2-mediated antigen-independent pathway of activation. Whereas CD8+ TIL did not respond to either stimulus the CD4+ TIL showed evidence of responder and nonresponder groups. In addition, we show that the deficient response obtained by triggering CD4+ TIL via the TCR can be restored by activation of the antigen-independent pathway. Finally, a total of 94 clones from four different TIL samples were obtained by limiting dilution and examined for their respective helper and cytolytic capabilities: 57% of the CD4+ TIL clones were able to produce interleukin 2 and 93% of the CD8+ TIL clones demonstrated cytolytic activity mediated by the T-cell receptor complex, indicating that the functional potential of proliferating TIL is intact.

Aged↗
PubMed1988

Proliferative and cytolytic potentials of purified human tumor-infiltrating T lymphocytes. Impaired response to mitogen-driven stimulation despite T-cell receptor expression.

Using limiting dilution analysis (LDA) we have previously shown that in most instances, the frequency (F) of proliferative T lymphocyte precursors (PTL-P) was strikingly reduced in tumor-infiltrating lymphocytes (TIL). In this study involving 19 cases, we show that the impaired clonogenic potential of CD2+ TILs is primarily caused by an intrinsic defect rather than to suppressor T cells or to a direct effect of the tumor cells usually present in the culture system. This was demonstrated by experiments in which the F of PTL-Ps was quantitated both in highly purified CD2+ TILs (using a cell-sorter) and in non-purified TIL suspensions (still containing tumor cells), which originated from the same biopsy specimen. The F of PTL-Ps was virtually identical in either sorted or nonsorted suspensions and the data from LDA were always consistent with the single-hit Poisson model, indicating that no suppressor cells interfered with growth of CD2+ TIL. Stimulation of sorted CD2+ TIL in low-density cultures by either phytohemagglutinin or anti-CD3-monoclonal antibody (MAb) indicated that the antigen-dependent activation pathway was impaired, although structurally intact T-cell receptor (TCR) complexes were apparently expressed, as assessed by immunofluorescence. The depressed proliferative response of CD2+ TIL could not be reversed in vitro when phorbol-esters were used in combination with ionomycin, which bypass the TCR. Nevertheless, 180 clones obtained from 8 cases were analyzed for their cytolytic activity. The majority mediated specific lytic activity (against unknown antigens), as assessed by lectin-dependent cell cytotoxicity, whereas only 6% of them manifested lymphokine-activated killing on appropriate targets.

Antigens, Differentiation, T-Lymphocyte↗