Recombinant allergens for immunotherapy: A Der p 2 variant with reduced IgE reactivity retains T-cell epitopes☆☆☆★★★ (original) (raw)
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PubMed, 2006
Several studies have shown that the presence of IgE antibodies to house dust mites (HDM), particularly Dermatophagoides pteronyssinus (Dpt), is an important risk factor for asthma. Allergen immunotherapy is indicated for patients with IgE antibodies to clinically relevant allergens. The aims of this study were to analyze the levels of specific serum IgE to Der p 1 and Der p 2 allergens in mite-sensitized atopic patients and to compare them with both in vivo (skin prick test) and in vitro (IgE-ELISA) sensitizations to Dpt crude extract. Forty-seven atopic patients with allergic rhinitis with or without intermittent or persistent mild asthma and positive skin prick test (SPT) to Dpt total extract were studied. Thirty age-matched healthy subjects with negative SPT to HDM were included as controls. Levels of total IgE and Dpt-, Der p 1- and Der p 2-specific IgE were measured by ELISAs in SPT-positive atopic patients and SPT-negative control subjects. Among 47 symptomatic atopic patients, 27 (57.4%) were double positive IgE to Der p 1 and Der p 2 allergens, 3 (6.4%) were single positive IgE to Der p 1, 4 (8.5%) were single positive IgE to Der p 2, and 13 (27.6%) were double negative IgE to both allergens. There was a significant correlation between Der p 1- and Der p 2-specific IgE levels, but not between Der p 1- or Der p 2-IgE levels and SPT results. The double negative IgE patients had the smallest skin test reactions although they showed high mean levels of total serum IgE. Therefore, the knowledge of specific IgE levels to Der p 1 and Der p 2 major allergens might support physicians for indication or follow-up in mite-sensitized patients under allergen-specific immunotherapy. These approaches might be important for obtaining improved safety and efficacy of the current clinical practice of allergen immunotherapy.
Journal of Allergy and Clinical Immunology, 1994
Background: Group H allergens are a major cause of sensitization in patients allergic to mites. To facilitate the antigenic analysis of group II allergens and to develop improved methods of allergen detection, we compared IgG anti-group H antibody responses in inbred mouse strains and raised a panel of monoclonal antibodies (mAbs). Methods: IgE antibody responses were compared by antigen-binding radioimmunoassay. Epitope specificity of the mAbs was analyzed by two-site binding assays and by cross-inhibition radioimmunoassays. Results: Comparison of polyclonal IgG antibody responses in five BALB congenic strains showed that H-2 a mice had poor responses, whereas H-2 b and H-2 k mice had strong, cross-reactive, IgG anti-group H responses. The specificities of nine anti-Der p H IgE mAbs raised in A/J mice were compared with specificities of seven m,4bs produced previously. Most mAbs (11 of 16) recognized common epitopes on Der p H and Der f 11: three were specific to Der p 11, and two showed high binding to Der f 11. Epitope analysis showed that the mAbs defined four cross-reactive, nonoverlapping sites on the group 11 allergens. Binding of several combinations of mAbs was compared, and a two-site ELISA for group 11 antigens was developed. Linear regression analysis showed an excellent correlation between results of this assay and group H radioimmunoassay of house dust samples (n = 40, r = O. 85, p < O. 001). Conclusions: There are multiple cross-reactive B-cell epitopes on group H allergens. The group H ELISA has several important applications, including assessment of environmental allergen exposure, monitoring of the efficacy of avoidance procedures, and standardization of commercial mite allergen extracts. (J ALLERGY CLIN IMMUNOL 1994;94:537-46.)
Functional inactivation of Dermatophagoides spp. (house dust mite) reactive human T-cell clones
Clinical <html_ent glyph="@amp;" ascii="&"/> Experimental Allergy, 1991
Staphylococcal enterotoxins are abie both to stimulate powerful polyclonal proliferative responses and to induce non-responsiveness of T lymphocytes expressing the appropriate T-cell antigen receptor Vfi gene products. T-cell clones representative of the human response to house dust mite were identified that express either V/?3 or V^6 gene products. The specificity of the latter was confirmed by seroiogy. Pre-treatment of cloned V^3 * T cells with the Staphylococcusaureus enterotoxins B or Cl rendered them non-responsive to immunogenic challenge with their natural ligand, while retaining responsiveness to exogenous IL-2. Similarly, exposure ofthe V/f6^ dust mite reactive T cells to the staphylococcal enterotoxin ofthe appropriate specificity, SEE, induced specific anergy. The development of non-responsiveness was associated with changes in the T-cell phenotypes. Downregulation of the T-cell receptor, Ti-CD3, was paralleled by enhanced expression of bot^h CD2 and the IL-2 receptor, CD25. Differential comodulation of CD4 and Ti-CD3 suggested that for some T cells CD4 may form part of the specific antigen recognition structure. Toxicity ofthe staphylococcal enterotoxins may be removed by chemical modification, thus their ability functionally to inactivate subpopulations of T cells expressing antigen-specific receptors with shared characteristics may beofpotentialvalueintheregulationof allergic diseases if the diversity of the T-cell repertoire proves to be limited.
Journal of Allergy and Clinical Immunology, 2001
However, the mechanisms through which SIT acts are less clear. We have recently shown that allergens may induce an activation-induced cell death process in lymphocytes from SIT-treated atopic patients. Objective: This study aimed to determine whether allergeninduced apoptosis can occur in a specific subset of cells. Methods: The study was performed in lymphocytes from normal subjects and atopic patients, some of whom were treated with SIT. Cells were cultured in the presence of gramineous pollen (Lolium perenne) allergenic extracts. Cell phenotype and intracellular cytokine expression were measured by means of fluorescent mAbs. Apoptosis was measured by using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling. Fluorescence was analyzed in a FAC-Scan flow cytometer, and the data were evaluated with Consort 30 software.
International Archives of Allergy and Immunology, 2001
Background: The major allergen of the dust mite Lepidoglyphus destructor, Lep d 2, has been produced as a recombinant allergen (rLep d 2) with IgE reactivity both in vivo and in vitro. A modified form of rLep d 2 (rLep d 2.6Cys) obtained by site-directed mutagenesis has been shown to have a reduced IgE reactivity in vitro. In this study we have compared the ability of rLep d 2 and rLep d 2.6Cys to elicit positive skin prick tests and cellular responses among L. destructor-sensitized subjects. Methods: Seventeen subjects were skin prick-tested with rLep d 2, rLep d 2.6Cys, histamine and negative controls and 17–20 h later skin biopsy specimens were taken from the skin prick-tested sites. The biopsy specimens were stained immunohistochemically for EG2+, CD3+, CD1a+, mast cell tryptase+, and IgE+ cells. Dermal cell infiltrates were judged in hematoxylin and eosin staining. Total IgE and allergen-specific IgE were determined by CAP-RAST. Results: Compared to rLep d 2, rLep d 2.6Cys indu...
Allergologia et immunopathologia, 2006
Background: CD8 + T suppressor cells may play a role in immunoregulation. Recent studies have characterized this population by the lack of the CD28 molecule. These CD8 + CD28-T cells differ phenotypically and functionally from CD8 + CD28 + T cells. Little is known about CD8 + CD28cells in atopy. Our aim was to analyze the phenotype and functional properties of CD8 + CD28-T cells in atopic and non-atopic individuals. Methods: Peripheral blood mononuclear cells (PBMC) were obtained after density gradient centrifugation. CD8 + CD28and CD8 + CD28 + T cells were isolated using immunomagnetic beads. Relative percentages of these cells and expression of several phenotypic markers were analyzed by flow cytometry. Proliferation was assessed by thymidine incorporation in isolated populations and in co-cultures with PBMC using Dermatophagoides pteronyssinus as stimulus. Cytokine synthesis was evaluated in culture supernatants by cytometric bead array. Results: The relative percentages of CD8 + CD28-T cells and their phenotypic expression in atopic and non-atopic volunteers were not significantly different. However, CD8 + CD28-T cells showed greater proliferation than did CD8 + CD28 + T cells when stimulated with D. pteronyssinus, although cytokine synthesis patterns were similar. CD8 + CD28co-cultures with PBMC showed greater proliferation than CD8 + CD28 + T cell co-cultures, but cytokine synthesis patterns were not different. Conclusions: Our data confirm phenotypic and functional differences between CD28 + and CD28-T cells, irrespective of atopic status. Purified human CD8 + CD28-T cells, freshly isolated from peripheral blood, do not have suppressor properties on allergen-specific proliferation or on cytokine synthesis in PBMC.
Epicutaneous immunotherapy on intact skin using a new delivery system in a murine model of allergy
Clinical & Experimental Allergy, 2009
Background Allergen-specific immunotherapy, subcutaneous immunotherapy (SCIT) or oral, has been used for almost a century to redirect inappropriate immune responses in atopic patients. A new mode of administration through the intact skin [epicutaneous immunotherapy (EPIT)], using an original epicutaneous delivery system, may represent an alternative to these classical methods.
European annals of allergy and clinical immunology, 2012
T cell receptor excision circles (TREC) on CD31+ T cells are related to recent thymic emigrant cells (RTEs). The involvement of the functional thymic tissue occurs early in the IgE-mediated allergic reaction, and in response to specific immunotherapy (SIT). Evaluation of specific immunotherapy effects on TREC number in peripheral T cells in patients allergic to Dermatophagoides pteronyssinus (Dpt). 85 respiratory allergic patients (both genders), 41 of them (Group II) under maintenance treatment to Dpt SIT (21 sublingual-SLIT, and 20 subcutaneous-SCIT), were selected. The allergic patients (Group I) without specific treatment were submitted to an allergen challenge test (22 nasal and 22 conjunctival). Peripheral cell analysis was performed immediately before treatment and 60 or 240 minutes after allergenic extract administration. TREC quantification was performed in CD4+CD31+ and CD8+CD31+. The results were expressed per 100.000 cells related to RTEs. Samples from 10 healthy individ...