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Biomedical subjects

B M Stadler

Publications and source records attributed to B M Stadler.

At least 55 records · Page 3Linked to original sources
PubMed1995

IgE-producing hybridomas established after B-cell culture in the CD40 system.

While total IgE synthesis can be easily induced in human PBL or B cells by different stimuli, no systems are known for the induction of allergen-specific IgE in vitro. In this study we investigated whether a specific Ig response could be induced using the CD40 culture system with the final intention to generate B-cell hybridomas secreting IgE of defined specificity. B cells derived from immunized donors normally give rise to many specific hybridomas after cell fusion. However, if cultured in the CD40 system and then immortalized and screened for anti-tetanus specificity, no tetanus-specific clones were found but a large number of IgE-secreting hybridomas had been generated. Also allergen-specific B cells could not be expanded in the CD40 system but long-term cultures yielded again B cells that were efficiently immortalized by cell fusion resulting in stable IgE-secreting hybridomas but of undefined specificity. One of these IgE-producing clones was further characterized and had an IgE production rate of 4.5 micrograms/10(6) cells/24 h. This paper provides two findings. (1) Our cell lines represent a valuable new source of human IgE. (2) Most importantly, our data indicate that the CD40 system is not suitable to expand specific B cells, suggesting that other systems have to be developed for the induction of a significant antigen-specific Ig response.

Allergens↗
PubMed1995

Polyclonal preparations of anti-tetanus toxoid antibodies derived from a combinatorial library confer protection.

We have compared the in vivo therapeutic potential of anti-tetanus toxin (TT) human Fab antibodies derived from a combinatorial phage display library to established polyclonal and monoclonal reagents. The oligoclonality and fine specificity distribution of the synthetic anti-TT Fab preparations was comparable to the antibody spectrum present in the donor serum and the affinities determined for the synthetic phage-bound Fab (Phab) and soluble Fab were in the same range as their monoclonal and polyclonal counterparts. On a weight basis, the protective capacity of the new oligoclonal preparations in vivo (16.4 IU/100 micrograms Fab) was comparable to those of the best combinations of hybridoma derived human monoclonal antibodies, and far better than those exhibited by the polyclonal serum antibodies of the donor (0.29 IU/100 micrograms IgG) or by a standard commercial human tetanus immunoglobulin preparation. These data suggest that recombinant antibodies may become a safe and effective alternative to human plasma-derived immunoglobulins for passive immunization.

Animals↗
PubMed1995

IgE autoantibodies in atopic dermatitis--occurrence of different antibodies against the CH3 and the CH4 epitopes of IgE.

Levels of "free" anti-IgE autoantibodies and IgE/anti-IgE immune complexes were measured in the sera of patients with atopic dermatitis before and after treatment, psoriasis patients, and nonatopic controls. In this measurement, we used two monoclonal antibodies with distinct in vitro functions (LE 27, BSW 17), directed against the epsilon CH3 and CH4 domains of the IgE Fc-fragment, in a novel immunobinding assay. In patients with atopic dermatitis, elevated levels of "free" anti-IgE antibodies and IgE/anti-IgE immune complexes were detected in comparison to psoriasis patients and controls. In addition, there was a positive correlation between total IgE and the amount of IgE/anti-IgE complexes detected by LE 27 (r = 0.7; P < 0.001) or BSW 17 (r = 0.64; P < 0.001) in patients with atopic dermatitis. In contrast, an inverse correlation was observed between total IgE and "free" anti-IgE antibodies (r = -0.34; P < or = 0.05) in atopic dermatitis. However, serum levels of anti-IgE autoantibodies before and after therapy in patients with atopic dermatitis did not differ, and levels of anti-IgE antibodies did not correlate with clinical severity, as evaluated by an established clinical scoring system. Our data clearly indicate that significantly elevated amounts of anti-IgE antibodies could be observed in patients with atopic dermatitis, which are directed against different epitopes on the IgE molecule. It is tempting to speculate that these autoantibodies exert different effects of IgE-receptor-bearing effector cells and may play an important role in IgE regulation.

Adolescent↗
PubMed1995

Anti-IgE autoantibodies and bee-sting allergy.

Serum anti-IgE autoantibodies (aaIgE) were investigated by dot immunobinding assay in bee-allergic patients in comparison with nonallergic beekeepers, healthy blood donors, and atopic subjects. Elevated serum levels of aaIgE--either free or combined with IgE--were found in both bee-allergic patients and atopic subjects as compared with beekeepers and healthy donors. With regard to a possible significance of aaIgE for the protective mechanism induced by specific allergen immunotherapy, we estimated aaIgE in bee-allergic patients before, during, and after bee-venom immunotherapy (BVIT) in relation to the outcome of a provocation test with a living bee (PT). During the first year of BVIT, there was no significant change in either free or combined aaIgE, but aaIgE decreased during protracted BVIT over 3-7 years. By using two monoclonal anti-IgE antibodies with different epitope specificity (Le27 and BSW17), we were able to detect two kinds of IgE/aaIgE immune complexes. Our data show that during and after BVIT the levels of one kind of IgE-aaIgE immune complex (the non-BSW17 type) tended to decrease in PT-negative patients but stayed elevated in PT-positive patients. The levels of the other kind of immune complex (the non-Le27 type) were similar in treatment failures and successfully treated patients. These data suggest that there are various kinds of aaIgE with different in vivo functions related to their epitope specificity. Some of them (non-BSW17 type) might be associated with BVIT failure.

Adult↗
PubMed1994

Human anti-IgE antibodies by repertoire cloning.

Anti-IgE antibodies have been detected in sera of patients with an allergic disease where they might play a role in the regulation of (Ig)E-mediated reactions. Using a recombinant phage surface display expression system a combinatorial library of antibody heavy and light chains was constructed from peripheral blood mononuclear cells from an atopic donor immunized with tetanus toxoid. Screening of the library allowed the identification of a large number of phages displaying human monovalent antigen-binding fragments (Phab) against tetanus toxoid and IgE. Surprisingly, we found a high frequency of Phab against particular IgE myelomas that was comparable to the frequency found for Phab against tetanus toxoid. However, most of these Phab were directed to different idiotypic determinants, depending on the IgE myeloma used for the panning procedure. Nevertheless, two clones were found to have anti-isotypic specificity and were shown to react specifically with the CH2 domain of the IgE heavy chain.

Adult↗
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↗
PubMed1994

Autoimmune and neuroendocrine regulation of the allergic response.

Allergic reactions seem to be under a variety of different control systems. Concerning the onset of allergic disease, it has become clear that cytokines play an important regulatory role. Specific T-Helper cells subsets produce a pattern of cytokines that preferentially induces IgE synthesis. As IgE synthesis always occurs in the normal individual, we propose that an additional control system is needed. Naturally occurring anti-IgE autoantibodies may represent such a control system that are capable to neutralise IgE or to eliminate IgE producing B cells. This hypothesis is also supported by our recent cloning of autoantibodies against IgE from the human genome. Interestingly, the brain seems to represent a superseding control system that is also capable of modulating allergic reactions and this even at the level of IgE synthesis. This control is mediated by neuroendocrine factors that influence the cytokine microenvironment as if a shift in the TH1/TH2 phenotype had occurred.

Antibodies, Anti-Idiotypic↗
PubMed1994

Anti-IgE autoantibodies in asthma: a diagnostic artefact or an explanation for non-allergic asthma?

Autoantibodies to IgE can be detected in sera of individuals with atopic disease, but occasionally elevated levels are also found in sera of normal individuals. During the last years we studied therefore the functional properties of such autoantibodies. Depending on the studied in vitro system one can always detect minimally two different antibody types. Antibodies have been found that either trigger or inhibit mediator release from basophils, that enhance or inhibit binding of IgE to the low IgE receptor and either stimulate or inhibit human IgE synthesis. Based on such in vitro experiments one may conclude that also in vivo autoantibodies exist that either neutralize IgE or have no effect on IgE mediated clinical events. Thus, anti-IgE autoantibodies may hide IgE as for example in those bee sting allergic individuals where we could not detect specific IgE but found IgE hidden within immune complexes, suggesting that the biological activity of IgE was not neutralized. A similar phenomenon may exist in asthmatic individuals. In a recent study we found that non-atopic asthmatic children had indeed low levels of serum IgE, but showed the same levels of autoantibodies to IgE, against suggesting that IgE was hidden within immune complexes. Thus, our ongoing research addresses the question whether in diseases of unclear atopic origin IgE may nevertheless play a critical role but based on possible artefacts in the IgE detection assays some of the clinically relevant IgE may escape.

Asthma↗
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

Immunotherapy with aluminum hydroxide adsorbed insect venom extracts (Alutard SQ): immunologic and clinical results of a prospective study over 3 years.

This prospective study over 3 years investigated the safety, immunogenicity, and effectiveness of immunotherapy (IT) with aluminum hydroxide adsorbed insect venom extracts (Alutard SQ, ALK Laboratories) in patients with previous, severe, systemic, IgE-mediated, anaphylactic reactions to Hymenoptera stings. Seventeen patients were treated with honeybee venom (BV), 13 with yellow-jacket venom (YJV), and 5 with both. No severe reactions to IT were noted. Only 3 BV-allergic patients experienced mild systemic reactions of grades I or II (1 per 139 injections) during the increase phase. As for the immunologic data, there was a significant decrease in specific IgE antibodies after 1 year, and a significant increase in specific IgG and IgG4 antibodies on reaching the maintenance dose, with a further rise after 1, 2, and 3 years. Moreover, a significant decrease in anti-IgE autoantibodies was observed in the BV group. Out of the 11 patients that were occasionally restung by the relevant insect (totaling 19 stings in all), only one patient developed mild systemic allergic symptoms after a third sting. In view of these results, we consider IT with aluminum hydroxide adsorbed insect venom extracts to be safe, immunogenic, and effective. The low rate of side-effects may be due to the slow release of the venom in the aluminum hydroxide adsorbed form.

Adolescent↗
PubMed1993

Interfering factors to sensitivity and specificity of bronchial reactivity in children.

Bronchial reactivity to carbachol, estimated by the PD65, the provocation dose of inhaled carbachol inducing a 65% increase of baseline respiratory resistance, was measured in 355 asthmatic children (age 8.7 +/- 2.6 years) and 149 healthy children (age 11.8 +/- 2.3 years). The frequency distribution of PD65 showed apart from 2 minima at 480 micrograms and 960 micrograms 2 significant peaks at 240 micrograms (p = 0.003) and 1200 micrograms (p = 0.01) to carbachol, reflecting a hyperreactive class (PD65 < 480 micrograms), an intermediate class (481 micrograms < PD65 < 960 micrograms) and a normo-reactive class (PD65 > 961 micrograms). The intermediate class is characterised by a considerable overlap between "health" and "disease". However, taking into account the degree of air pollution in which healthy children are living (best related factor to specificity) and the type of initial lung function disorder in asthmatic children, (the MEF50 to be the best related factor for specificity), weighed specificity and sensitivity improved from 64 to 88%. Evaluating bronchial responsiveness in children, such interfering factors should be strongly considered.

Adolescent↗
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

Anti-IgE autoantibodies mistaken for specific IgG.

During isolation of specific IgE by affinity chromatography, we obtained IgG acting as "specific IgG" in dot immunoassay and RAST. Further analysis of this fraction revealed that this specific IgG was indeed an immune complex consisting of IgG anti-IgE autoantibodies and specific IgE that falsely appeared as specific IgG in the immunoassays. After disruption of complexes, more IgE became accessible, resulting in increased counts per minute in the RAST. Thus, anti-IgE autoantibodies may hinder determination of specific IgE in in vitro immunoassays, since they hide specific IgE immunologically. To demonstrate the isotope specificity of such immune complex-derived IgG, the purified anti-IgE autoantibodies were radiolabeled and used as detection antibodies in immunoblotting. These autoantibodies recognized different IgE preparations, including a recombinant IgE peptide.

Adult↗