Biomedical subjects

Wayne R Thomas

Publications and source records attributed to Wayne R Thomas.

10 recordsLinked to original sources

PubMed2006

IgE and IgG anti-house dust mite specificities in allergic disease.

BACKGROUND: There are few studies that quantitatively compare IgE and IgG antibody binding to the major and minor house dust mite allergens. OBJECTIVE: To measure the IgE and IgG antibody specificities produced by adults and children, including children admitted to an emergency department for asthma. METHODS: Antibodies were measured by solid-phase microtiter assays. RESULTS: Children recruited from the emergency department had similar titers and patterns of IgE antibody binding compared with children without acute disease. Der p 1 and 2 bound 50% to 65% of the IgE antibody, and most of the remaining binding was to Der p 4, 5, and 7. Der p 3, 8, 10, and 20 induced low titers. The pattern was similar across a wide range of antihouse dust mite titers. IgG(1) and IgG(4) antibodies predominantly bound the major and midrange allergens and were mainly found in children with allergy. Children recruited in the emergency department had lower titers. CONCLUSION: The same IgE antibody-binding pattern and predominant contribution of Der p 1 and 2 was found across a wide range of total IgE antibody titers and for children admitted to an emergency department. IgG(1) and IgG(4) antibodies bound to the more allergenic specificities and were largely found in children with allergy. The IgG antibody titers were lower in sera from children admitted to the emergency department for asthma exacerbations. CLINICAL IMPLICATIONS: Der p 1 and 2 and possibly Der p 4, 5, and 7 provide a formulation suitable for immunotherapy and diagnosis. Low IgG antibodies were a feature of acute disease.

Adolescent↗

PubMed2005

Downregulation of IgE antibody and allergic responses in the lung by epidermal biolistic microparticle delivery.

BACKGROUND: Biolistic injections provide a needle-free delivery of antigen-laden microparticles to the epithelium. The precision of the injection preferentially targets the Langerhans cell network, which, although ideal for vaccination, might not be suitable for the downregulation of immune responses in immunotherapy. OBJECTIVE: We sought to determine the ability of biolistic injection of antigen into the epithelium of sensitized mice to inhibit IgE antibody and lung inflammatory responses produced by further exposure to antigen. METHODS: Mice were sensitized by means of a needle injection of ovalbumin (OVA) in alum and given a series of biolistic injections of OVA or vehicle control, followed by a boost of OVA in alum. Serum IgE and IgG antibodies were measured before and after the boost. The mice were then challenged intranasally, and the infiltration of inflammatory cells was measured by means of bronchoalveolar lavage. Airway reactivity of the challenged mice was measured by examining responses to methacholine with forced oscillatory techniques. RESULTS: Biolistic injection of OVA into the dorsal skin of sensitized mice markedly inhibited IgE and IgG1 antibody responses induced by boosting. IgG2a antibody responses were reduced rather than stimulated. The eosinophilic inflammation in the bronchoalveolar lavage fluid induced by intranasal challenge was also markedly inhibited. Lung hyperreactivity showed an initial increase and then a decrease of responsiveness to methacholine, with elastance returning to the level of unsensitized mice. Biolistic injection into the buccal epithelium was also inhibitory. CONCLUSIONS: Biolistic injection of allergen inhibited the boosting of IgE antibody and eosinophilic lung inflammatory responses without inducing T(H)1 immunity.

Animals↗

PubMed2005

Structural biology of allergens.

Major allergens may have special aerobiological properties and allergenic structures. It would also be instructive to consider the properties of nonallergens and nonallergenic responses. In some cases, nonallergenic responses appear to result from a lack of antigenicity and in others from regulation. Proteolytic activity has been proposed as an adjuvant for allergenicity, but lipid binding is far more common and is found for more than 50% of the major allergens. Such structures can enhance allergenicity via Toll-like receptor (TLR) or CD1 pathways. TLR signaling can enhance both Th1 and Th2 responses and be induced by peptides as well as nonproteinaceous ligands.

Allergens↗

PubMed2005

Genetically engineered vaccines.

The application of recombinant DNA technology to allergen research has provided the sequence information and genetic material to produce new types of allergy vaccines. One general strategy has been to use the knowledge to produce synthetic peptides that represent selected T-cell or B-cell epitopes. The production of genetically engineered allergens provides an alternative strategy to construct hypoallergenic vaccines, which can provide a better and less selected representation of the epitopes. Many strategies have been used to produce such hypoallergens, and their ability to reduce allergenicity has been amply demonstrated by skin and nasal provocation tests. The retention of T cell-stimulating activity has also been demonstrated, and a consistent feature of the vaccines has been, despite the reduced immunoglobulin E (IgE)-binding reactivity, the ability to induce anti-allergen IgG antibody. The lead hypoallergens have been polypeptide fragments and trimeric constructs of the birch allergen Bet v 1. A clinical trial with these medicaments has shown the ability to modify IgE and IgG antibody production, skin test reactivity, and symptom scores. This is the first trial of a recombinant allergy vaccine, and it has set a benchmark for further studies. A new generation of hypoallergens is now being produced based on the detailed knowledge of the tertiary structures of the allergens and of the T-cell and B-cell epitopes. The modifications have been made to change the topography of the allergens while retaining a stable, folding structure. In the case of Bet v 1, tertiary structures of hypoallergens have been determined. Structurally modeled hypoallergens have been produced for pollen, venom, food, and latex allergens, with promising characteristics from preclinical studies.

Allergens↗

PubMed2004

Isoforms of the major peanut allergen Ara h 2: IgE binding in children with peanut allergy.

BACKGROUND: The major peanut allergen Ara h 2 consists of two isoforms, namely Ara h 2.0101 and Ara h 2.0201. The recently identified Ara h 2.0201 isoform contains an extra 12 amino acids including an extra copy of the reported immunodominant epitope DPYSPS. This study aimed to evaluate the IgE binding of the two Ara h 2 isoforms. METHODS: Ten clones of Ara h 2 were sequenced to assess the relative frequency of the Ara h 2 isoforms and to identify whether there was further variation in the Ara h 2 sequence. IgE binding to Ara h 2.0101 and Ara h 2.0201 was measured for 70 peanut-allergic children using an IgE DELFIA assay to quantitate specific IgE binding. A competition assay was used to measure whether Ara h 2.0201 contained IgE epitopes other than those found for Ara h 2.0101. RESULTS: The original Ara h 2.0101 sequence was found for 6/10 clones and Ara h 2.0201 was found for 2/10 clones. Ara h 2.0201 had the expected insertion of 12 amino acids as well as substitutions at positions 40 (40G) and 142 (142E). Two new isoforms were identified as different polymorphisms of position 142. One Ara h 2.01 clone (Ara h 2.0102) contained 142E and one Ara h 2.02 clone (Ara h 2.0202) contained 142D. A polymorphism that was previously identified by other investigators at position 77 (77Q or 77R) was not found for any of the 10 sequences. Although the level of IgE binding to Ara h 2.0201 of individual patients was frequently higher than the binding to Ara h 2.0101 (p < 0.01), there was a strong correlation in binding to both isoforms (r = 0.987, p < 0.0001) and when analyzed as a group the means were similar. Ara h 2.0101 was not as efficient at blocking reactivity to Ara h 2.0201 indicating there is an additional IgE specificity for the Ara h 2.0201 isoform. CONCLUSIONS: Ara h 2.0201 has similar but higher IgE binding than the originally sequenced Ara h 2.0101 isoform and contains other IgE specificities.

2S Albumins, Plant↗

PubMed2004

Adjuvant costimulation during secondary antigen challenge directs qualitative aspects of oral tolerance induction, particularly during the neonatal period.

In this report we demonstrate that although passive feeding of specific Ag to mice as neonates or adults can induce oral tolerance in both the cellular and humoral arms of the immune response, quantitative and, in particular, qualitative aspects of the tolerance process are determined by the nature of the inflammatory costimuli provided at the time of secondary Ag challenge. Moreover, this dependency upon nonspecific costimulation is more profound in Ag-fed neonates than in their adult counterparts. Thus, administration of Ag in the Th1-selective adjuvant CFA to prefed animals resulted in significant inhibition of IgG2a, IL-2, and IFN-gamma responses, whereas IL-5 responses were increased. In contrast, rechallenge with Ag in the Th2-selective adjuvant aluminum hydroxide resulted in significant inhibition of IgG1, IgE, IL-2, and IL-5 responses, whereas IFN-gamma responses were increased. Additionally, although soluble Ag challenge of prefed adults revealed marginal tolerogenic effects, the same challenge protocol in animals prefed as neonates elicited enhanced Th2-dependent IgG1 production. These results suggest that inflammatory stimulation at the time of Ag challenge is obligatory to trigger oral tolerance mechanisms, particularly in animals fed as neonates and also that the type of adjuvant used at the time of challenge selects for the type of Th cell population to be inhibited.

Administration, Oral↗

PubMed2004

Recombinant allergens for analysing T-cell responses.

T-cell responses constitute a central element of allergic disease and a model for studying Th1 and Th2 cytokine pathways. Most studies to date have used extracts of allergens which contain variable quantities of different allergens and non-allergenic antigens. Recombinant allergens provide the tools for studying the responses to allergens in a reproducible and dose-dependent manner and the different T-cell responses of allergic and non-allergic subjects provide a method for verifying the responses and their relationship to allergic sensitisation. Most allergies show dominant responses to one or a few major allergens. These allergens have been described for the common allergies and have been produced as recombinant allergens. A particular problem for allergens is that many are mixtures of proteins from multi-gene families or are highly polymorphic. Information now exists so the sequence variation can be represented. Purified recombinant allergens produced by standard expression systems stimulate the expected T-cell responses from the peripheral blood of allergic and non-allergics to allergen extracts. Although stimulation with recombinant allergens which are not produced with a natural IgE binding activity can provide a measure of allergenicity, the altered tertiary structure can reduce Th2 responses. The sequence information now available provides the means to use PCR to produce cDNA for the production of recombinant allergens from readily available sources. The production of the highly reactive recombinant Der p 2 allergen of house dust mite from natural sources is described.

Allergens↗

PubMed2004

The allergenic specificities of the house dust mite.

The most important house dust mites are Dermatophagoides pteronyssinus and in drier areas D. farinae. In subtropical and tropical regions the glycyphagid mite Blomia tropicalis is a major source of allergen, which co-exists with D. pteronyssinus. The group 1 and 2 allergens of Dermatophagoides mites are clearly major specificities and it is likely that these allergens could be the basis of new strategies of immunotherapy for many mite-allergic subjects. About 20% of patients, however, do not have IgE antibody to the group 1 and 2 allergens, and even though this is a minority, it constitutes a large population. There are also many other house dust mite allergens which have high IgE binding activity but these are present in low and variable concentrations in mite extracts, usually at less than 1% of the group 1 and 2 allergens. It must be appreciated that mite extracts are arbitrary preparations that do not accurately represent the relative concentrations of allergens in inhaled air. There is now the opportunity to produce more representative and more balanced formulations of allergens, possibly by mixtures of recombinant allergens. It is likely that the group 3, 5, 7 and 9 allergens will be important along with the high molecular weight group 11, 14, 15 and 18. The tropomyosin group 10 may be an important cross-reacting allergen. B. tropicalis is, because of its distribution in highly populated regions with increasing affluence, a very important allergen. It has low-grade cross-reactivity with Dermatophagoides but most allergens only have 30-40% sequence identity between the different families so they require different allergens for immunotherapy and new diagnostic measures are required to distinguish the sensitivity between the mite families. Studies on B. tropicalis allergens are required to identify the major allergens that do not appear to be the group land 2 specificities. Component resolved diagnosis is a newly developing procedure that uses allergen arrays to provide a diagnostic format to differentiate between cross-reacting allergens and to identify the optimal formulation of allergens for different patients.

Allergens↗

PubMed2002

Hypersensitivity reactions after respiratory sensitization: effect of intranasal peptides containing T-cell epitopes.

BACKGROUND: The intranasal administration of peptides containing T-cell epitopes has been shown to inhibit T-cell and antibody responses of mice injected with allergen, but responses to respiratory sensitization might be regulated differently. OBJECTIVE: This study was designed to examine the effect of intranasal peptide on antigen-induced lung inflammatory responses and delayed hypersensitivity after sensitization by the respiratory mucosa or without sensitization. METHODS: Mice were treated with an intranasal tolerizing regimen of a peptide containing the major T-cell epitope of Der p 1. Delayed hypersensitivity and lung inflammation to challenge with Der p 1 was measured either without further treatment or after sensitization induced by means of the intranasal administration of Der p 1 with a mutated enterotoxin adjuvant. Lung inflammatory responses were examined by means of lavage and histologic section, and delayed hypersensitivity responses were measured on the basis of ear swelling. RESULTS: Delayed hypersensitivity reactions were induced in mice treated with intranasal peptide, and large reactions were found in mice given intranasal peptide and sensitized with intranasal Der p 1 and adjuvant. Mice pretreated with peptide and sensitized with Der p 1 had an increased lymphocytic infiltration after allergen-specific challenge, as measured by means of bronchoalveolar lavage and shown histologically. These hypersensitivity results are in contrast to previous data that show tolerance to injected antigen. CONCLUSIONS: Although the intranasal administration of a peptide containing a T-cell epitope markedly inhibits responses to sensitization produced by the injection of allergen, the peptide induces immune responses and increases hypersensitivity to respiratory sensitization.

Administration, Intranasal↗

PubMed2002

Characterization and immunobiology of house dust mite allergens.

The examination of house dust mite extracts has indicated that over 30 different proteins can induce IgE antibody in patients allergic to the house dust mite. There are however dominant specificities especially the group 1 and 2 allergens which can account for much of the allergenicity of extracts. Of the 19 denominated allergens, the major IgE binding has been reported for the group 1, 2, 3, 9, 11, 14 and 15 allergens. The high-molecular-weight group 11, 14 and 15 allergens have only recently been described and although high IgE binding has been anticipated from immunoblotting, there is a need for considerable corroboration. Similarly, the study of the group 3 and 9 serine protease allergens has been incomplete. The group 4, 5, 7 and 8 allergens have shown intermediate IgE binding and the group 10 tropomyosins are of interest because of their potential cross-reactivity with allergen from disparate species. Although the progress with the production of recombinant group 1 allergens has been recent, many of the allergens can be produced as high IgE-binding polypeptides. The tertiary structure of the group 2 allergens has been determined from recombinant proteins and they are an excellent model for the investigation of modified allergens. An unexpected property of the group 1, 2 and 3 allergens has been the high degree of polymorphism found by cDNA analysis. It has however been possible to identify sequences to represent the variation in the natural allergens. The group 7 and 14 allergens show secondary modifications which vary in different extracts creating batch variation. While some estimate of the importance of allergens can be obtained from IgE binding, few analyses of T-cell responses have been made and these regulate both the development of, and the protection from sensitization.

Allergens↗