Allergen-specific Reactivity Research Articles

Coexistence of nasal reactivity to allergens with and without IgE sensitization in patients with allergic rhinitis.

Allergic rhinitis (AR) and local allergic rhinitis (LAR) are defined by nasal reactivity to aeroallergens with and without positive skin prick test (SPT), respectively. In this study, we aimed to investigate whether both types of allergen-specific reactivity can coexist in the same individual. Forty-eight patients with perennial rhinitis symptoms and positive SPT with seasonal allergens only (discrepant group) were subjected to consecutive nasal allergen challenges (NAC) with seasonal (NAC-S) and perennial allergens (NAC-P). A nasal lavage was collected before and after the NACs to measure eosinophil cationic protein (ECP). A basophil activation test (BAT) with seasonal and/or perennial allergens was performed in ten patients from the discrepant group and in six seasonal allergic rhinitis (SAR), eight perennial local allergic rhinitis (LAR), six nonallergic rhinitis (NAR), and six healthy control (HC) individuals. All patients in the discrepant group tested positive in the NAC-S, and 41 of them (85.4%), also in the NAC-P (group A). Conversely, seven patients tested negative in the NAC-P (group B). ECP in the nasal lavage increased after the NAC-P in the group A (P=.004), but not in the group B. The BAT with seasonal allergens was positive in 100% of SAR and group A cases, whereas the BAT with perennial allergens was positive in 37.5% and 60% of LAR and group A cases, respectively. All NAR and HC subjects tested negative for the BAT. This study shows that nasal reactivity to aeroallergens with and without positive SPT can coexist in the same patient. We propose the term dual allergic rhinitis for this rhinitis phenotype.

ASCIA‐P38: AN ALLERGENOMIC APPROACH FOR IDENTIFICATION OF NOVEL AIR‐BORNE ALLERGENS AFFECTING CRAB‐PROCESSING WORKERS DUE TO INHALATIONAL EXPOSURE

Occupational exposure and sensitization to food proteins and allergens is a serious health concern, and affects 4-36% of the workforce in the seafood industry. Although there have been previous attempts to identify and characterize air-borne food allergens, there is still a poor correlation between the inhalational exposure and allergen-specific reactivity among the seafood processing workers. The aim of this study was to implement a combined proteomic- and allergenomic-based strategy to identify the major IgE-reactive proteins in crab processing factory among sensitized workers and investigate the inhalational allergen load for major crab allergens. Twenty crab-processing workers were recruited for this study with clinical asthma and/or positive skin prick test to crab extract. Air-borne allergen load was measured by sampling air from the personal breathing zones of the workers. IgE antibody reactivity to king and edible crab allergens were analysed using serum from worker by immunoblotting and mass spectrometric characterization of allergens. 90% of the tested crab workers showed strong IgE binding and recognition to crab proteins. Strong IgE reactivity was observed to crab tropomyosin and arginine kinase. Unique IgE binding patterns were observed to different raw and heated crab extracts. In addition, IgE binding to novel putative allergens such as hemocyanin were observed. The current study provides an insight into the role of major crab allergens, which maybe be the primary sensitizer in the development of allergy and asthma in the crab industry. The outcome of this study assists in better work safety for workers at risk of developing ingestion-induced food allergy and future development of immunotherapeutic strategies.

Immune Regulation by CD4+CD25+ Regulatory T Cells in Patients with Japanese Cedar Pollinosis

Background: Evidence indicating that CD4+CD25+ regulatory T (Treg) cells play a crucial role in the maintenance of peripheral T cell tolerance to allergens has been accumulated. To explore the functional role of Treg cells in patients with Japanese cedar pollinosis, we performed an in vitro investigation of the regulation of immune responses to allergens by Treg cells. Methods: CD4+ and CD4+CD25– T cells obtained from 12 patients with Japanese cedar pollinosis were stimulated with Cry j 1 protein and Cry j 1-derived peptide. On day 6, T cells were tested for allergen-specific reactivity using a CFSE-based proliferation assay and cytokine ELISA assays. The frequency of Cry j 1-specific interleukin (IL)-10-producing Treg cells was assessed by ELISPOT assays. Results: The proportion of proliferated cells induced by allergen stimulation was similar in both CD4+ and CD4+CD25– cell cultures. The production of interferon (IFN)-γ, but not that of IL-5 was significantly enhanced in CD4+CD25– cell cultures compared to that in CD4+ cell cultures. Interestingly, the production of IL-10 was decreased in CD4+CD25– cell cultures. Moreover, Cry j 1-specific IL-10-producing Treg cells were detected in pollen-allergic patients. Conclusion: Our findings suggest that in pollen-allergic patients, Treg cells predominantly suppresses Th1 responses rather than Th2 responses, where allergen-specific IL-10-producing Treg cells may also be responsible for the downregulation of allergen-specific immune responses.

The current state of recombinant allergens for immunotherapy

Subcutaneous immunotherapy is a well documented treatment of allergic rhinitis and asthma. The majority of the disadvantages of the treatment are related to the poor quality of the natural allergen extracts which can contain varying amounts of individual allergens including allergens to which the patient may not be sensitized. Recombinant allergens offer a possibility to use well defined molecules with consistent pharmaceutical quality defined in mass units. The proof of concept of the clinical efficacy of recombinant allergens is based on two studies published as full articles. One study applied a mixture of five Phleum pratense major allergens in a maximum dose of 40mcg protein. The clinical efficacy showed a significant efficacy with 40% reduction in disease severity. The second study compared a commercial birch extract with both recombinant Bet v 1 and purified Bet v 1 in dosages of 15mcg allergen. The clinical effect was 60% additional efficacy. Systemic side effects occurred more frequently with grass allergens. A third study used hypoallergenic fragments and a trimer of Bet v 1. The study did not show efficacy and a rather high frequency of systemic side effects. The advantages of using recombinant allergens for immunotherapy are obvious but more studies on a large scale are needed before the overall value in terms of efficacy and safety can be assessed. Clinical trials are also necessary for new combined vaccines based on recombinant allergens that in experimental studies have shown greatly enhanced immunogenicity and low allergen-specific reactivity.

Changes in intracellular cyclic adenosine monophosphate levels in peripheral blood leukocytes during immunotherapy with vespid venom

The allergen-induced release of mediators from basophils is known to be decreased after rush venom immunotherapy (VIT) compared with pretreatment values. A rise in the intracellular cyclic adenosine monophosphate (cAMP) level is known to inhibit mediator release. To determine changes in cAMP levels in peripheral blood leukocytes (PBLs) during rush VIT and to evaluate their relation to allergen-specific reactivity of basophils. Ten patients allergic to vespid venom (VV) were investigated before rush VIT and after reaching the maintenance dose. Five VV-allergic patients not undergoing VIT served as controls. Patients' PBLs were incubated with VV, and allergen-induced histamine and leukotriene release from basophils was measured. Levels of cAMP were determined in PBLs and in plasma. Immediately after rush VIT, VV-induced histamine release (P = .04) and VV-induced leukotriene release (P = .01) were significantly reduced. Intracellular cAMP levels increased significantly (P = .047). However, 6 months after VIT, mediator responses in basophils were comparable with pre-VIT values. No significant changes were found in the control group. An increase in intracellular cAMP levels might account for the decreased reactivity of basophils to allergen after 1 week of VIT. However, similar to the decreased mediator release after 1 week of VIT, this is not a long-term effect as values returned to baseline after 6 months.

Clustered sensitivity to fungi: anaphylactic reactions caused by ingestive allergy to yeasts

Respiratory allergy to environmental molds is relatively common, and fungal allergen-specific reactivity seems to cluster in certain persons. However, generalized reactions caused by ingested fungi have seldom been described. To describe a mold-sensitized patient who developed multiple anaphylactic reactions after ingesting a yeast preparation widely used by the food industry as flavoring in, for example, powdered and ready-made sauces. Skin prick tests and serum IgE tests were performed with inhalant and food allergens, including molds and yeasts, 2 pasta sauces consumed by the patient, individual sauce ingredients, and a food-quality yeast extract. Radioallergosorbent test inhibition was used for specificity studies. Skin prick and serum IgE test results were positive to several molds (Cladosporium herbarum, Alternaria alternata, Aspergillus fumigatus, and Penicillium notatum), baker's yeast (Saccharomyces cerevisiae), Malassezia furfur, and champignon and to the 2 pasta sauces, the yeast ingredient, and a food-quality yeast extract. Radioallergosorbent test inhibition studies confirmed that the sauces contain cross-reacting yeast and mold allergens. This patient has a clustered sensitization to fungi characterized by allergy to environmental fungal allergens and to yeast extracts used in the food industry. Yeasts should be considered as possible ingestive allergens in mold-allergic patients.

A chimeric human-cat Fcγ-Fel d1 fusion protein inhibits systemic, pulmonary, and cutaneous allergic reactivity to intratracheal challenge in mice sensitized to Fel d1, the major cat allergen

Co-aggregation of FcεRI with FcγRIIb can block FcεRI-mediated reactivity and Fc gamma:allergen chimeric proteins, by co-crosslinking FcγRIIb to allergen-specific IgE bound to the FcεRI can block allergen-specific reactivity. We evaluated whether a human cat chimeric fusion protein (GFD) composed of part of the human Ig G1 Fc fused to the major cat allergen (Fel d1) would function as allergen immunotherapy while not inducing acute allergic reactivity in mice sensitized to Fel d1. Injection of GFD 6 h prior to Fel d1 challenge acutely blocked systemic and skin reactivity to Fel d1 challenge while mice given subcutaneous immunotherapy with GFD at days 37, 38, and 39 showed inhibition of systemic, lung, and cutaneous reactivity to Fel d1 2 weeks later. GFD immunotherapy did not induce systemic reactivity. Overall, the Fcγ-Fel d1 chimeric fusion protein blocked Fel d1-induced IgE-mediated reactivity but did not induce in vivo mediator release on its own; suggesting that this approach using allergen combined with Fc gamma1 so as to achieve inhibitory signaling may provide an enhanced form of allergen immunotherapy.

The Editors’ Choice

Allergen-specific reactivity at birth is now a commonly described phenomenon, and interest in this observation is heightened by the association between altered immunologic reactivity at this time and subsequent development of atopy. The lymphoid tissue or tissues in which antigen priming occurs during fetal development are not known, but in this issue of the Journal, Jones et al (p 235 ) provide evidence that the fetal gut is a plausible site at which antigen priming can occur. MHC class II+ cells, CD3+ T cells, and cells expressing the costimulatory molecules required to initiate an antigen-specific immune response are all present from 16 to 19 weeks of gestation, as are dietary antigen and cytokines (in amniotic fluid) that favor a TH2-biased response.

Detection of house-dust-mite allergen in amniotic fluid and umbilical-cord blood

Mononuclear cells in umbilical-cord blood display allergen-specific reactivity, but how allergen exposure occurs in utero is unknown. We investigated the presence of a common inhalant allergen (Der p 1), to which mothers are exposed throughout pregnancy, by ELISA in matched maternal blood and amniotic fluid samples at 16-17 weeks of gestation, and in matched maternal and umbilical-cord blood at term (> or =37 weeks of gestation). Der p 1 was detectable in 24 of 43 amniotic fluid samples where it was also present in maternal blood, and in 15 of 24 cord-plasma samples at significantly higher concentrations than in the maternal plasma (p=0.022). The detection of Der p 1 in the amniotic fluid and the fetal circulation provides direct evidence of transamniotic and transplacental allergen exposure.