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T Werfel

Publications and source records attributed to T Werfel.

At least 73 records · Page 4Linked to original sources
PubMed1999

C3a(desArg) does not bind to and signal through the human C3a receptor.

Contradictory results have been published in the past regarding the functional responses of different cell types to the anaphylatoxin C3a and its natural catabolite C3a(desArg). To elucidate the interaction of the C3a receptor (C3aR) with its ligand(s) we studied the binding of human recombinant C3a (rC3a) and rC3a(desArg) to RBL-2H3 transfectants which express the C3aR. As the addition of 11 aminoterminal amino acids did not alter the functional activity of the recombinant C3a as compared to serum-derived C3a the specific binding of rC3a and rC3a(desArg) to the transfectants could be determined by flow cytometry using a monoclonal antibody (mab) against their N-terminal histidine tag. Recombinant C3a bound to the C3aR with a half maximal concentration of about 3 nM whereas no evidence for a binding of rC3a(desArg) could be obtained. Furthermore, rC3a(desArg) did not signal through the C3aR. Neither the release of lysosomal N-acetyl-beta-D-glucosaminidase nor the directional migration of C3aR-expressing RBL-2H3 transfectants could be detected in response to rC3a(desArg) whereas rC3a was highly active in both assays. Our data demonstrate a defined ligand specificity of the C3aR for the anaphylatoxin C3a. Its natural catabolite C3a(desArg), however, does not signal through the C3aR. Modulating effects of C3a(desArg) on the synthesis of cytokines in human monocytes and B lymphocytes may therefore be induced by receptor-independent mechanisms while their in vivo relevance remains as yet undefined.

Acetylglucosaminidase↗
PubMed1999

Birch pollen-related foods trigger atopic dermatitis in patients with specific cutaneous T-cell responses to birch pollen antigens.

BACKGROUND: Patients with inhalant allergy caused by birch pollen frequently demonstrate immediate symptoms to cross-reactive fruits, vegetables, or both. The nature of late eczematous reactions to pollen related food antigens has not been investigated in detail. OBJECTIVE: The purpose of this study was to find out whether isolated late eczematous reactions to birch pollen-related food antigens can be observed in patients with atopic dermatitis (AD) who are highly sensitized to birch pollen antigens. A possible linkage of such reactions with specific T-cell responses to birch pollen antigens in the blood and lesional skin was examined as well. METHODS: We examined 37 adult patients with AD and hypersensitivity to birch pollen but without any history of immediate responses to food challenges. These patients underwent an elimination diet, including all birch pollen-related food antigens, followed by a double-blind, placebo-controlled, oral provocation. Blood and skin biopsy specimens were taken to examine a birch pollen-specific lymphocyte response. RESULTS: Seventeen patients reacted with a deterioration of AD symptoms. Food- or birch pollen-specific IgE did not differentiate these patients from nonreactive patients. A significantly higher increase in the proportion of blood lymphocytes expressing the cutaneous lymphocyte antigen on incubation with birch pollen antigens was found in cells from reactive compared with nonreactive patients. The proliferative response of skin-derived T-cell lines from reactive patients to birch pollen extract or Bet v 1 was significantly higher than that of nonreactive patients. An enrichment of more than 25% of T-lymphocyte subpopulations defined by T-cell receptor-Vbeta elements was detected in the majority of such antigen-stimulated T-cell lines from responsive patients. A higher frequency of birch pollen-reactive T cells was calculated from limiting-dilution assays, and a higher rate of birch pollen-specific T-cell clones was generated from cultures with skin-derived T cells from reactive patients. CONCLUSION: Our results show, for the first time, that a subpopulation of patients with hypersensitivity to birch pollen and AD reacts with worsening of eczema after oral challenge with birch pollen-related foods and that a birch pollen-specific T-cell response can be found in the lesional skin of these patients.

Administration, Oral↗
PubMed1999

Atopy patch test reactions are associated with T lymphocyte-mediated allergen-specific immune responses in atopic dermatitis.

BACKGROUND: Positive test reactions to epicutaneous application of aeroallergens served as a model of 'early' eczema in atopic dermatitis (AD) in a number of dermato-immunological studies. However, no quantitative evaluation has been performed so far comparing specific T-cell activation parameters in the peripheral blood of AD patients with positive or negative atopy patch tests (APT). OBJECTIVE: The purpose of this study was to investigate specific immunological parameters in patients with atopic dermatitis showing positive or negative atopy patch tests reactions. METHODS: APT results (n = 96) were compared with allergen-specific IgE, specific lymphocyte proliferation, and the expression of 'activation' markers on peripheral blood T-cells upon in vitro stimulation with house dust mite, cat or grass pollen allergens. RESULTS: Only a subpopulation (48%) of patients sensitized to aeroallergens (i.e. specific IgE > 0.7 kU/L) developed APT-reactions to the corresponding allergen. APT reactions were, however, significantly associated with allergen specific lymphocyte proliferation (p < 0.0001), and a higher number of CD54+ or CD30+ T-cells (p < 0.05) upon in vitro stimulation. CONCLUSION: The association of delayed skin reactions with allergen specific T-cell parameters in the blood points to an immunologically mediated mechanism leading to positive reactions in the APT.

Allergens↗
PubMed1999

Evaluation of C3a receptor expression on human leucocytes by the use of novel monoclonal antibodies.

Varying results have been published in the past regarding the reactivity of different leucocyte subpopulations, including neutrophils, monocytes and B lymphocytes, to the anaphylatoxin C3a and its degradation product C3a(desArg). To better characterize the cellular distribution of C3a receptor (C3aR) expression, monoclonal antibodies against two different epitopes on the third extracellular domain of the human C3aR were generated. Quantification of C3aR as compared with C5aR densities was performed on peripheral blood leucocytes by quantitative indirect immunofluorescence. Eosinophils and basophils expressed similar numbers of C3aR and C5aR molecules/cell. On eosinophils 10 700+/-4500 (mean+/-SD) C3aR and 14 700+/-4100 C5aR were found, whereas basophils carried 8100+/-2100 C3aR and 13 500+/-3800 C5aR. Monocytes expressed approximately six times more C5aR than C3aR molecules on their surface (6000+/-2500 C3aR versus 34 100+/-9300 C5aR molecules) whereas on neutrophils, the expression of C5aR was more than 20 times higher than the expression of C3aR (3100+/-1000 C3aR versus 63 500+/-12 200 C5aR). No C3aR expression was detectable on peripheral blood-derived B lymphocytes and on tonsillar B cells before and after stimulation with interleukin-2/Staphylococcus aureus Cowan strain I. Our findings correspond well with the paucity of data on C3a-induced functional activities in monocytes and neutrophils and suggest that eosinophilic and basophilic granulocytes represent the primary effector cells in the peripheral blood which can be stimulated by C3a.

Animals↗
PubMed1999

Validity study for the stigmatization experience in atopic dermatitis and psoriatic patients.

A central experience of patients with atopic dermatitis and psoriasis is the feeling of stigmatization. This can be estimated by the "Questionnaire on Experience with Skin Complaints" (QES), based on the "Feelings of Stigmatization Questionnaire" by Ginsburg & Link. This study was designed to evaluate the psychometric properties of the QES, especially the validity of this questionnaire, and to supply more information about the stigmatization experiences of patients with atopic dermatitis and psoriasis. Three groups of patients were analysed: 76 with atopic dermatitis, 81 and 217 with psoriasis, respectively. The comparison of subgroups with different affected regions revealed that the genital region is especially relevant for the stigmatization experience in these patients. In addition, the feeling of stigmatization (estimated by the QES) is relatively independent of the different dimensions of the "Trier Scales of Coping with Diseases", except for the depressive coping style "Rumination" measuring a high amount of inner concern with the afflicting disease. It can be concluded that the QES is a valid and reliable instrument for examining the stigmatization experience of patients with atopic dermatitis and psoriasis.

Adaptation, Psychological↗
PubMed1998

Human eosinophils produce biologically active IL-12: implications for control of T cell responses.

The present study assessed the capacity of eosinophils (EOS) to synthesize the cytokine IL-12. Blood-derived, highly purified human EOS from six atopic patients and two nonatopic individuals were treated in culture with IL-4, IL-5, granulocyte-macrophage CSF, IFN-gamma, TNF-alpha, IL-1alpha, RANTES, and complement 5a, respectively. The expression of both IL-12 protein and mRNAs for the p35 and p40 IL-12 subunits was strongly induced in all donors by the Th2-like cytokines IL-4 and granulocyte-macrophage CSF and was also moderately induced by TNF-alpha and IL-1alpha. IL-5 treatment resulted in IL-12 synthesis in four atopic donors and one nonatopic donor, whereas IFN-gamma induced IL-12 synthesis in only two atopic donors. In contrast, RANTES exclusively induced mRNA for the p40 subunit without detectable protein release, and complement 5a had no effect on IL-12 mRNA or protein expression. EOS-derived IL-12 was biologically active, because supernatants derived from IL-4-treated EOS superinduced the Con A-induced expression of IFN-gamma by a human Th1-like T cell line. This activity was neutralized by anti-IL-12 Abs. In conclusion, EOS secrete biologically active IL-12 after treatment with selected cytokines, which mainly represent the Th2-like type. Consequently, EOS may promote a switch from Th2-like to Th1-like immune responses in atopic and parasitic diseases.

Cell Line↗
PubMed1998

Anaphylatoxin C3a but not C3a(desArg) is a chemotaxin for the mouse macrophage cell line J774.

Varying results have been published regarding the functional reactivity of different cell types, including human monocytes, to the anaphylatoxin C3a and its degradation product C3a(desArg). To further delineate the functions of C3a and C3a(desArg) on this cell type we used the murine macrophage (Mø) cell line J774A.1 which is known to respond to the anaphylatoxin C5a. J774 cells specifically bound fluorescein isothiocyanate-labeled recombinant human C3a (rC3a). The cells migrated along rC3a concentration gradients in a dose-dependent manner with an optimal concentration of about 3 nM (rC5a:7 nM) and a half-maximal effective concentration (EC50) of about 1.2 nM (rC5a: 2 nM). The degradation product rC3a(desArg) was devoid of chemotactic activity. mRNA for the recently cloned G protein-coupled mouse high-affinity C3a receptor (C3aR) was detected in J774 cells, suggesting that this receptor represents the binding site for C3a on J774 Mø. In support of the specific nature of C3a-stimulated cellular mobility, RBL-2H3 transfectants expressing the human C3aR were also shown to migrate along gradients of rC3a (optimal concentration about 8 nM; EC50 about 3.5 nM) whereas rC3a(desArg) was again inactive. In summary, our findings demonstrate for the first time a specific, receptor-mediated chemoattraction of cells of the monocytic lineage to the anaphylatoxin C3a which may contribute to the accumulation of Mø at sites of inflammation.

Animals↗
PubMed1998

The human mast cell line HMC-1 binds and responds to C3a but not C3a(desArg).

Controversial results have been published in the past regarding the functional reactivity of different cell types to the anaphylatoxin C3a and its degradation product C3a(desArg). To understand better the effects of C3a and C3a(desArg) on human mast cells, the authors performed binding experiments and calcium mobilization studies on the human mast cell line HMC-1 which has been shown previously to express C3a binding sites. For this purpose, functionally active, recombinant C3a (rC3a) was constructed with an 11 amino acid peptide attached to the N-terminus of the molecule. Using a monoclonal antibody (MoAb) against this tag, binding of rC3a to HMC-1 cells could be demonstrated by flow cytometry. Its binding was specific as it could be blocked with serum-derived C3a. In contrast, no binding of rC3a(desArg) to HMC-1 cells was detectable. Recombinant C3a led to a transient mobilization of intracellular calcium [Ca2+]i in HMC-1 which was inhibitable by the C3a-specific MoAb K13/16. No increase of [Ca2+]i was detected when the cells were treated with C3a(desArg). The authors found C3a receptor (C3aR)-specific mRNA in HMC-1 cells indicating that this receptor represents the binding site for C3a on these cells. These results demonstrate a specific binding for C3a but not for C3a(desArg) on cells of the human mast cell line HMC-1. As a consequence, functional activity was restricted to C3a with C3a(desArg) being completely inactive. Therefore, the data strongly suggest that the recently cloned high affinity C3aR which is assumed to represent the binding site for the anaphylatoxin on HMC-1 cells is unresponsive to C3a(desArg).

Animals↗
PubMed1998

Stress-induced endocrine and immunological changes in psoriasis patients and healthy controls. A preliminary study.

BACKGROUND: Clinical observations suggest that psychological stress can induce exacerbation of psoriasis. It is hypothesized that these stress effects on the course and outcome of psoriasis are caused by neuroendocrine modulation of immune functions. Therefore we investigated the cardiovascular, endocrine and immunological response to a laboratory stressor in psoriasis patients and healthy controls. METHODS: Untreated (n = 7) and PUVA-treated (n = 4) psoriatics and healthy controls (n = 7) were exposed to a brief laboratory stressor (public speaking and mental arithmetic). Heart rate and blood pressure, catecholamine, cortisol, and DHEA plasma concentration, as well as distribution of T and NK lymphocytes were analyzed before, immediately after and 1 h after stress exposure. RESULTS: Heart rate and blood pressure increased in all three groups during stress exposure with the most pronounced changes in PUVA-treated patients. Psoriasis patients displayed higher adrenaline values but diminished cortisol and DHEA plasma concentrations compared to controls. NK cell numbers (CD16+, CD56+), but not T lymphocyte subsets, increased immediately after stress exposure in untreated patients and controls. This effect was significantly diminished in PUVA-treated patients. CONCLUSIONS: The data of this pilot study indicate an enhanced stress-induced autonomic response and diminished pituitary-adrenal activity in psoriasis patients. PUVA treatment seems to interfere with the cardiovascular and NK cell response to acute psychological stress. Future studies will analyze the stress-induced neuroimmunological mechanisms in psoriatics in more detail.

Adult↗
PubMed1998

Prevalence of Helicobacter pylori-associated gastritis in chronic urticaria.

BACKGROUND: Chronic urticaria and concurrent angioedema are frustrating problems for both physicians and patients. METHODS: 100 patients with chronic urticaria (mean duration 33.3+/-48.2 months) attending the urticaria consulting hour of our Department of Dermatology within 1 year were carefully analyzed for pathogenesis to avoid extensive unnecessary diagnostic approach in the future. RESULTS: In 43 cases a potential infectious trigger could be identified, 35 were of idiopathic origin, and 15 demonstrated pseudoallergic reactions to acetylsalicylic acid or food additives, 5 had antibodies to thyroid gland, and 2 had malignant diseases. Of patients with foci, 26 had Helicobacter pylori-associated gastritis, 9 chronic tonsillitis or sinusitis, 4 infections with Epstein-Barr virus or cytomegalovirus, 2 dental focal infections and 2 suffered from Yersinia infection. High prevalence of H. pylori gastritis was found since 47% of patients showed elevated H. pylori-specific IgA and/or IgG antibodies. 27 patients underwent endoscopy and in all but 1 (96%) antral H. pylori infection was found. In contrast, a prevalence rate of 37% among asymptomatic adults has been published. Disappearance (67%) or improvement of urticaria (24%) occurred in most antimicrobially treated patients after 3-12 weeks. In contrast, only 50% of untreated H. pylori-seropositive patients with chronic urticaria showed spontaneous remission or improvement within 12 weeks. Prevalence of H. pylori infection may even be underestimated since only 27/100 patients underwent endoscopy. It is suggested that H. pylori infection may be present at least in all seropositive subjects (47%). Moreover, we found H. pylori infection in 2 seronegative subjects demonstrating gastric complaints. CONCLUSIONS: Thus, measurement of H. pylori-specific antibodies and/or gastroscopy should be included in the diagnostic management of chronic urticaria to identify patients who may profit from eradication treatment with disappearance of long-standing and annoying urticaria symptomatology.

Adolescent↗
PubMed1997

Evidence that singlet oxygen-induced human T helper cell apoptosis is the basic mechanism of ultraviolet-A radiation phototherapy.

Ultraviolet A (UVA) irradiation is effectively used to treat patients with atopic dermatitis and other T cell mediated, inflammatory skin diseases. In the present study, successful phototherapy of atopic dermatitis was found to result from UVA radiation-induced apoptosis in skin-infiltrating T helper cells, leading to T cell depletion from eczematous skin. In vitro, UVA radiation-induced human T helper cell apoptosis was mediated through the FAS/FAS-ligand system, which was activated in irradiated T cells as a consequence of singlet oxygen generation. These studies demonstrate that singlet oxygen is a potent trigger for the induction of human T cell apoptosis. They also identify singlet oxygen generation as a fundamental mechanism of action operative in phototherapy.

Antibodies, Blocking↗
PubMed1997

Dichotomy of blood- and skin-derived IL-4-producing allergen-specific T cells and restricted V beta repertoire in nickel-mediated contact dermatitis.

In this study we compared the phenotype and cytokine patterns of nickel-specific T cell clones (TCC) derived from blood samples and positive patch test reactions. A total of 252 nickel-specific TCC were established from three nonatopic patients with allergic contact dermatitis caused by nickel. All TCC expressed the TCR-alpha beta, and 77% were CD4+ compared with 21% CD8+ TCC. In contrast to blood-derived TCC, the majority of skin-derived CD4+ or CD8+ T lymphocytes produced IL-4 either in combination with IFN-gamma (type 0 cytokine pattern) or IL-4 exclusively (type 2 pattern). Skin-derived nickel-specific TCC of each patient secreted significantly more IL-4 than blood-derived TCC of the same individual. Analysis of TCR-V beta repertoire from two patients indicated that >40% of the tested TCC expressed one of the following V beta elements: V beta 13.1/13.2, V beta 20, V beta 2, V beta 6.7, or V beta 14. Only 20% of unstimulated T cells but >40% of nickel-stimulated T cells derived from peripheral blood of the same individuals expressed these V beta elements, suggesting a selection of certain TCR-V beta elements by nickel sulfate in these patients. In contrast to the compartmentalization of IL-4 production, there were no major differences in the expression of TCR-V beta elements between blood- and skin-derived nickel-specific TCC. These results point to a modulation of the cytokine production pattern of T lymphocytes after their migration from peripheral blood into the skin and a production of the type 2 cytokine IL-4 in acute eczematous lesions in nonatopic individuals.

Allergens↗
PubMed1997

Blood- and skin-derived monocytes/macrophages respond to C3a but not to C3a(desArg) with a transient release of calcium via a pertussis toxin-sensitive signal transduction pathway.

Controversial results have been published in the past regarding the functional reactivity of monocytes (Mo) and macrophages (M phi) to the anaphylatoxin C3a and its degradation product C3a(desArg). In this study we performed binding and calcium mobilization experiments with recombinant human C3a (rC3a) and rC3a(desArg). Blood Mo displayed non-inhibitable binding of FITC-labeled rC3a (rC3aFITC) but responded to rC3a with a transient release of the intracellular calcium concentration ([Ca2+]i), whereas rC3a(desArg) was completely inactive. In contrast, binding of rC3aFITC to eosinophilic granulocytes and the mast cell line HMC-1 which have been shown previously to express C3a binding sites could be blocked by a monoclonal anti-C3a antibody. The rC3a-induced [Ca2+]i release in blood Mo was pertussis toxin (PTX)-sensitive suggesting the involvement of G-proteins in the signal transduction pathway. Skin-derived Mo/M phi reacted similarly to blood Mo as no specific binding of rC3aFITC to these cells could be demonstrated, whereas an intracellular release of calcium ions in response to the anaphylatoxin was observed. Homologous desensitization to rC3a but not heterologous desensitization to rC5a was detected in further experiments. The functional effect of C3a, but not the unspecific binding of rC3aFITC to blood Mo and skin-derived Mo/M phi could be blocked by the monoclonal anti-C3a antibody. These results suggest the expression of the recently cloned G-protein-coupled receptor for C3a on human blood Mo and skin-derived Mo/M phi. However, the total number of specific C3a binding sites on these cells is distinctly lower as compared to eosinophilic granulocytes and cells of the mast cell line HMC-1. The small number of C3a receptors on Mo/M phi may be masked by a pronounced non-inhibitable binding of rC3aFITC. This binding, however, may contribute to the recently described biological effects of C3a(desArg) on Mo.

Arginine↗