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Notes: Background The dust mite Lepidoglyphus destructor is an important cause of allergic reactions to dust, especially in farming environments. Two isoforms, recombinant (r)Lep d 2.01 and rLep d 2.02, of the major allergen Lep d 2, have previously been expressed as recombinant proteins. These isoforms differ 10.4% at the amino acid level. Furthermore, a mutant form of Lep d 2.01 (rLep d 2.6Cys) with a highly reduced IgE reactivity, has also been produced.Objective To investigate the T cell responses to the recombinant isoforms of Lep d 2, the Lep d 2.6Cys mutant and peptides of Lep d 2, in allergic and non-allergic individuals.Methods Peripheral blood mononuclear cells from 18 allergic and 16 non-allergic individuals were stimulated with the different antigens and the proliferative responses were measured. The cytokine production (interleukin (IL)-4, IL-5 and interferon (IFN)-γ) were measured by ELISA.Results Higher T cell proliferation was measured to isoform 01 than to 02 in 28/34 subjects. The responses to rLep d 2.6Cys were lower than to isoform 01 in most subjects, but higher than to Lep d 2.02. Two immuno-dominant peptides, corresponding to amino acid residue 11–25 and 61–75 were identified. The atopic subjects produced significantly lower IFN-γ in response to Lep d 2.01 as compared to the non-atopics.Conclusions There was a significant difference in T cell response between the two isoforms of rLep d 2. The hypoallergenic mutant rLep d 2.6Cys was able to evoke a T cell response with a magnitude which is between the two isoforms. Amino acid residue 11–25 and 61–75 are the most frequently recognized parts of Lep d 2 and are likely to contain the immuno-dominant T cell epitopes.

Notes: Background Exposure to indoor allergens, such as dust mites, has been recognized as a risk factor for sensitization and symptoms.Objective To develop a two-site ELISA for the determination of Lep d 2 in the reservoir, to measure dust mite allergen exposure (Lep d 2, Der p 1, Der f 1 and Der 2) in farm households, and to investigate whether exposure to these allergens is associated with sensitization, asthma and rhinoconjunctivitis.Methods Monoclonal antibodies to recombinant (r)Lep d 2 were produced with standard hybridoma technique. Dust samples from 393 households were analysed for allergen content by two-site ELISA methods.Results A two-site Lep d 2 ELISA was developed with a detection limit of 0.09 µg/g. The assay was highly reproducible and levels of Lep d 2 showed a strong correlation with the number of Lepidoglyphus mites (rs: 0.7; P = 0.0002). Lep d 2 was detected in 20% of the homes; levels ranged from 0.09 to 1.7 µg/g of dust. Der p 1 was recorded in 59% of the samples, ranging from 0.055 to 139 µg/g, and Der f 1 and Der 2 in 40% and 50% of the samples, ranging from 0.055 to 24.5 µg/g and 24.3 µg/g, respectively. Dermatophagoides allergens were significantly higher in mattresses than in carpets (P 〈 0.0001), but this difference was not observed with Lep d 2. A strong relationship between immunoglobulin (Ig)E to rLep d 2 and asthma (OR = 10.4) and rhinoconjunctivitis (OR = 7.5) was seen. Furthermore, sensitization to D. pteronyssinus was significantly associated with asthma (OR: 13.7) and rhinoconjunctivitis (OR: 5.7).Conclusion When assessing mite allergen exposure in rural homes, not only the Der p 1, Der f 1 and Der 2 allergens, but also the Lep d 2 allergen should be taken into consideration.

Notes: Background The cause of the chronic inflammation in atopic keratoconjunctivitis (AKC), the ocular manifestation of atopic eczema/dermatitis syndrome, is largely unknown.Objective To investigate the possibility that microorganisms may be important in the inflammatory activity in AKC.Methods Fifteen patients with AKC participated in the study. The presence of aerobic bacteria and fungi was related to the severity of clinical signs, the numbers of inflammatory cells in tears and conjunctival biopsies, and the concentration of various cytokines in tears. In addition, serological evidence for IgE sensitization to Staphylococcus aureus B antigen and Malassezia sympodialis antigen was investigated. Twelve healthy subjects were included for control purposes.Results The patients exhibited moderate clinical signs of AKC. No relation was found between the severity of AKC and the presence of microorganisms, despite the fact that S. aureus was frequently isolated. AKC patients showed significantly higher levels of IFN-γ, TNF-α (tumour necrosis factor-α), IL-2, IL-4, IL-5 and IL-10 than controls. An association was found between conjunctival signs and the levels of all cytokines except IL-5.Conclusion We found no evidence to suggest that periocular and ocular microcolonization are related to inflammatory parameters in AKC. However, confirmation of the present results in a longitudinal study with repeated clinical examinations and samplings in the same individual is required before the contribution of S. aureus to on-going inflammation in AKC can be dismissed.

Notes: Background Allergen-specific immunotherapy is the only treatment for allergic disease providing long-lasting symptom relief. Currently, it is mainly based on the use of crude allergen extracts. The treatment may be improved by the use of genetically engineered allergens, hypoallergens, aiming at a more effective and safer therapy.Objective The aim of this study was to provide a rational design of hypoallergen candidates for immunotherapy by using structural information and knowledge of B and T cell epitopes of an allergen.Methods The three-dimensional structure of the major cat allergen Fel d 1 was systematically altered by duplication of selected T cell epitopes and disruption of disulphide bonds. Seven Fel d 1 derivatives were generated and screened for allergenic reactivity in comparison with recombinant Fel d 1 in competition-ELISA. The allergenicity was further evaluated in basophil activation experiments and T cell reactivity was assessed in a lymphoproliferation assay.Results Three out of seven Fel d 1 derivatives, with two duplicated T cell epitopes and one or two disulphide bonds disrupted, were carefully evaluated. The three derivatives displayed a strong reduction in allergenicity with 400–900 times lower IgE-binding capacity than recombinant Fel d 1. In addition, they induced a lower degree of basophil activation and similar or stronger T cell proliferation than recombinant Fel d 1.Conclusion By a rational approach, we have constructed three Fel d 1 hypoallergens with reduced IgE-binding capacities and retained T cell reactivities. This strategy may be applied to any well-characterized allergen to improve immunotherapy for allergic patients.

Notes: Background Polymorphisms within the β subunit of the high-affinity receptor for IgE (FcεR1-β) on chromosome 11q13 have been related to atopy and asthma and the lymphotoxin α (LTα) gene on chromosome 6 is implicated in asthma.Objective To elucidate the association of polymorphisms in the FcεR1-β and LTα genes to IgE responses and asthma in a family-orientated rural population.Methods A total of 461 adult farmers, who participated in an epidemiological follow-up study on respiratory symptoms among farmers on the Swedish island of Gotland, were examined. The traits assessed included serum total IgE, IgE antibody responses to 21 common inhalant allergens and asthma.Results The 237G mutation was only detected in seven persons. Atopy was found to be associated with the RsaI-ex7 AB-genotype (OR = 1.9; P = 0.04). The RsaI-ex7 B allele had a significant influence on IgE responses to pollens and dust mites (OR = 5.5; P = 0.03 and OR = 5.2; P = 0.049, respectively). The influence of this allele was stronger when the association towards single dust mite species (Lepidoglyphus destructor) was estimated (OR = 7.1, P = 0.03) and the association increased even more when the major allergen of L. destructor (rLep d 2) was analysed (OR = 11.2, P = 0.02). These associations were independent of sex, age and smoking, and the estimates of RsaI-in2 independent of RsaI-ex7. RsaI-in2, RsaI-ex7 and LTα genotypes were unassociated with total serum IgE. No significant difference in the distribution of RsaI-in2, RsaI-ex7 and LTα genotypes was found among subjects with atopy or asthma compared to healthy controls.Conclusion This study supports the notion that polymorphisms in the FcεR1-β gene have significant effects on IgE responsiveness. Secondly, dust mites in rural populations influence the expression of genes on chromosome 11q13.

Notes: Background Genetic engineering of the major birch pollen allergen (Bet v 1) has led to the generation of recombinant Bet v 1 derivatives with markedly reduced IgE-binding capacity, but with retained T cell activating ability.Objective To compare the mucosal reactivity to rBet v 1 derivatives with rBet v 1 wild-type as basis for new therapeutic strategies for birch pollen allergy based on mucosal tolerance induction.Methods Outside the pollen season, 10 patients with birch pollen allergic rhinitis and mild asthma underwent four nasal challenge-sessions in a randomized, double-blind, and cross-over design, employing increasing doses of rBet v 1 fragment mix, rBet v 1 trimer, rBet v 1 wild-type and diluent (albumin). Nasal lavage fluids (NAL) were collected before the challenge-series as well as 10 min, 4 and 24 h thereafter. Nasal lavage fluid levels of tryptase as well as EPO and ECP were measured as indices of mast cell and eosinophil activity, respectively.Results All 10 patients tolerated the highest accumulated dose, 8.124 µg, when challenged with rBet v 1 trimer, eight with rBet v 1 fragments compared to one when challenged with rBet v 1 wild-type. No late phase reactions were observed. The change in tryptase levels (pre-challenge vs. 10 min) was significantly lower after challenges with rBet v 1 trimer and rBet v 1 fragments than with rBet v 1 wild-type. The change in EPO/ECP concentration pre-challenge versus 4 h post-challenge was lower for rBet v 1 trimer and the change was significantly lower when pre-challenge versus 24 h post-challenge to rBet v 1 fragments and rBet v 1 wild-type was examined.Conclusion The derivatives induced significantly fewer symptoms and lower mast cell and eosinophil activation than rBet v 1 wild-type upon application to the nasal mucosa. They could in the future be candidates for immunotherapy based on mucosal tolerance induction.

Notes: Increased concentrations of mast cell tryptase in post mortem blood have frequently been observed in sudden infant deaths but the cause of this has not yet been clarified.〈section xml:id="abs1-2"〉〈title type="main"〉ObjectiveThe aim was to evaluate factors (immunological, morphological and anamnestic data) behind the observed increase in mast cell tryptase in sudden infant deaths with elevated tryptase.〈section xml:id="abs1-3"〉〈title type="main"〉MethodsMast cell tryptase and total immunoglobulin (Ig) E were measured in post mortem sera from 44 infants younger than 1.5 years. Radioallergosorbent tests were performed for possible allergens (mixture for relevant food allergens, Phadiatop and latex). IgG subclasses, IgM, and complement factors (C3, C4 and factor B) were measured with radial immunodiffusion. Mast cells, labelled with antibodies against mast cell tryptase, were counted in the lungs and heart. The circumstances of death and medical history of the deceased infant and family were obtained through police and hospital records.〈section xml:id="abs1-4"〉〈title type="main"〉ResultsIn 40% of the SIDS cases tryptase was elevated (〉10 μg/L). Total IgE in serum was increased in 33% compared with clinical reference values but showed no association with mast cell tryptase. RAST tests were positive in three cases. In one of these cases both tryptase and total IgE were elevated. The only variable that was associated with high tryptase values was prone position at death (P ≤ 0.05 ). Allergy or asthma in the family were alleged in 50% of the cases, but was not associated with elevated tryptase or IgE. Children with elevated total IgE also displayed high concentrations of IgG1 and IgG2. Infants who died in the spring had significantly higher IgE than the others (P ≤ 0.05).〈section xml:id="abs1-5"〉〈title type="main"〉ConclusionThe results do not support the hypothesis that the elevated tryptase concentrations in sudden infant death are caused by allergy. The association between prone position at death and elevated tryptase could hypothetically be explained by mast cell degranulation due to, for example, a hypoxic stimulus in these infants.

Notes: Several studies have confirmed the presence of animal dander allergens in school dust but the effect of this indirect animal exposure on health has not been evaluated. In this study we investigated bronchial reactivity and markers of eosinophil activity and inflammation during two separate weeks of school in 10 children with mild asthma and a positive skin prick test to cat and dog. At the beginning and the end of the first week the children underwent bronchial challenges with methacholine, and at the beginning and the end of the second week they underwent nasal lavages (NAL) and induced sputum samplings. Blood and urine samples for analysis of inflammatory markers were obtained before and after both school weeks. Peak expiratory flow (PEF) and symptoms of asthma and allergy were recorded daily, and spirometry was performed on each visit. The exposure to animal dander allergens was estimated from dust samples obtained in the subjects’ schools and homes. Bronchial sensitivity to methacholine increased in the week when this was measured. The proportion of eosinophils in peripheral blood, and urinary eosinophil protein X (EPX), decreased in both weeks. There was a trend towards an increase of eosinophil peroxidase (EPO) and myeloperoxidase (MPO) in sputum in the week when these proteins were measured. The concentrations of cat (Fel d1) and dog (Can f1) allergens were higher in dust collected in schools than in homes. Our results show that in children with mild asthma and animal dander allergy, there is a significantly increased bronchial sensitivity to methacholine after one school week. There is also a significant decrease in the number of circulating eosinophils and a trend towards an increase of sputum EPO, which could correlate with the early phase of eosinophil recruitment to the lungs. These effects may be related to the continuous exposure to animal allergens in school dust.

Notes: Allergen-specific immunotherapy (SIT) is commonly conducted with allergen extracts adsorbed to aluminium hydroxide (alum). Drawbacks linked to the use of alum, such as the formation of granuloma at the site of injection, have led to suggestions of novel allergen carriers. An alternative carrier is 2 μm carbohydrate-based particles (CBPs). In mouse, allergen-coupled CBPs have been demonstrated to skew the allergen-specific immune response towards a Th1-like activity (Grönlund et al. Immunology, 2002). We here coupled the recombinant major cat allergen Fel d 1 to CBPs (CBP-Fel d 1) by cyanogen-bromide activation, resulting in covalent binding. The effect of CBP-Fel d 1 on monocyte-derived dendritic cells (MDDCs) from healthy human blood donors was studied. We found that the majority of the CD1a+ MDDCs were capable of taking up FITC-labelled CBP-Fel d 1, as demonstrated by flow cytometry and confocal laser scanning microscopy. Furthermore, incubation with CBP-Fel d 1 resulted in an upregulation of the costimulatory molecule CD86 on the MDDCs, which was not observed with Fel d 1 or CBPs alone. Finally, CBP-Fel d 1 induced a fivefold increase in the release of the pro-inflammatory cytokine tumour necrosis factor (TNF)-α and a fourfold increase in the release of the chemokine interleukin-8 from MDDCs. Taken together, the effects CBPs possess make them interesting as novel allergen carriers for SIT.