M. Kronqvist

Clinical effects of immunotherapy with genetically modified recombinant birch pollen Bet v 1 derivatives

Background Birch pollen and pollen from related trees of the Fagales order are a major cause of allergic rhinitis, conjunctivitis, and asthma through the spring season in northern and central Europe.

Variability of IgE reactivity profiles among European mite allergic patients

Background  House dust mites (HDM) Dermatophagoides pteronyssinus are a frequent indoor allergen source. Our aim was to determine the frequencies of IgE reactivity to purified HDM allergen molecules in mite allergic patients from different parts of Europe in order to establish an allergen panel for diagnosis of HDM allergy.

Cytokine and Antibody Responses in Birch-Pollen-Allergic Patients Treated with Genetically Modified Derivatives of the Major Birch Pollen Allergen Bet v 1

Background: Recently, recombinant hypoallergenic derivatives of the major birch pollen allergen, Bet v 1, were used to treat birch-pollen-allergic patients in a double-blind, placebo-controlled, multi-centre immunotherapy study. The aim of this study was to evaluate the effects of vaccination with aluminium-hydroxide-adsorbed recombinant Bet v 1 derivatives versus placebo on T-cell, cytokine and antibody responses in a subgroup of patients. Methods: Blood was drawn from patients of the Swedish centre (n = 27; rBet v 1 fragments: n = 10; rBet v 1 trimer: n = 8, and placebo-aluminium hydroxide: n = 9) before the start and after completion of the treatment. PBMC were stimulated with rBet v 1 and analysed for cytokine (IL-4, IL-5, IL-10, IL-12, IL-13 and IFN-γ)-secreting cells by ELISpot. Bet v 1-specific antibody levels in serum (IgG1–4, IgE and IgA) were measured by ELISA. Skin prick tests with defined Bet v 1 concentrations were performed before and 10–11 months after the beginning of the study. Results: Bet v 1-specific IgG levels, consisting of IgG1, IgG2 and IgG4, were significantly increased after treatment with recombinant allergen derivatives. Treatment with rBet v 1 trimer led to a significant (p < 0.05) reduction of Bet v 1-reactive IL-5- and IL-13-producing cells, reflecting a reduced Th2 response. In addition, a decreased number of Bet v 1-reactive IL-4 producing (p = 0.07) and an increase of IL-12-producing (p = 0.06) cells was noted in the trimer-treated patients. In contrast to placebo, active treatment resulted in significantly reduced immediate-type skin reactions to Bet v 1 even 10–11 months after treatment. Conclusion: Vaccination with recombinant hypoallergenic Bet v 1 derivatives induces a Bet v 1-specific IgG response and leads to reduced skin reactivity in allergic patients. A reduction of Bet v 1-specific Th2 responses was observed in trimer-treated patients, which may reflect the intrinsic property of this allergen derivative.

Higher immunoglobulin E antibody levels to recombinant Fel d 1 in cat‐allergic children with asthma compared with rhinoconjunctivitis

Background Current diagnosis of allergy and asthma to cat is confirmed using cat dander extract (CDE). We have previously engineered a recombinant major cat allergen, rFel d 1, with properties identical to the natural molecule.

Risk factors associated with asthma and rhinoconjunctivitis among Swedish farmers

Background: Earlier studies have shown a high prevalence of respiratory symptoms in farming communities and that storage mites constitute important allergens. We examined risk factors associated with asthma and rhinoconjunctivitis among Swedish farmers.

Antibody profiles and self-reported symptoms to pollen-related food allergens in grass pollen-allergic patients from northern Europe

Background:  Most studies on pollen‐related food allergy have so far focused on the association of birch/weed pollen allergens and plant food allergy. The aim of this study was to elucidate the allergen spectrum among a group of grass pollen‐allergic patients from northern Europe and to relate the results to clinical histories of pollen‐related food allergy.

Exposure to an abundance of cat (Fel d 1) and dog (Can f 1) allergens in Swedish farming households

Background: Earlier studies have shown that farmers are to a low degree sensitized to animal allergens. We have measured the amount of cat (Fel d 1) and dog (Can f 1) in farm households and examined the relationship between exposure and sensitization to cat and dog allergens.

Evaluation of specific IgE to the recombinant group 2 mite allergens Lep d 2 and Tyr p 2 in the pharmacia CAP system

Background: Several recombinant allergens have been shown to be potentially useful for diagnosis of IgE–mediated allergy, but only a few recombinant allergens are at present commercially available in serological assays for detection of specific IgE. The aim of this study was to evaluate the IgE binding to the recombinant major dust mite allergens rLep d 2 and rTyr p 2 and compare it with the IgE binding to the commercial mite extracts Lepidoglyphus destructor and Tyrophagus putrescentiae in the Pharmacia RAST CAP System. Methods: The recombinant allergens rLep d 2 and rTyr p 2 were immobilised on ImmunoCAPs, and sera from 461 Swedish farmers who are frequently exposed to mites were analysed for specific IgE antibodies. Immunoblotting was performed to evaluate discrepancies between the results obtained with the recombinant and the commercial CAP assays. Results: The IgE values of each recombinant assay significantly correlated with the IgE values of the corresponding commercial CAP assay. The sensitivity of the rLep d 2 assay was 73.3% and that of the rTyr p 2 assay, 60.5% of that provided by the commercial L. destructor and T. putrescentiae assays. Two subjects out of 416, who tested negative in the commercial L. destructor assay, were positive to rLep d 2. The corresponding figures for rTyr p 2 and the T. putrescentiae extract were 5/418. The possibility that these subjects were sensitised to L. destructor and T. putrescentiae could not be excluded. Conclusions: The data suggest that it may be possible to use rLep d 2 and rTyr p 2 on ImmunoCAPs to detect and quantify IgE antibodies to these, the major allergens of L. destructor and T. putrescentiae. It appears likely that the addition of just a few more recombinant L. destructor and T. putrescentiae allergens in the CAP assay will be sufficient for in vitro diagnosis of IgE mediated allergy to L. destructor and T. putrescentiae.

Associations of FceεR1‐bβ polymorphisms with immunoglobin E antibody responses to common inhalant allergens in a rural population

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.

A Hypoallergenic Derivative of the Major Allergen of the Dust Mite Lepidoglyphus destructor, Lep d 2.6Cys, Induces Less IgE Reactivity and Cellular Response in the Skin than Recombinant Lep d 2

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 induced significantly smaller and fewer skin prick test reactions (p < 0.001) and dermal cell infiltrates (p < 0.05). Further, rLep d 2.6Cys induced fewer EG2+ cells (p < 0.001) but more tryptase+ cells (p < 0.05) than rLep d 2. A positive RAST to rLep d 2 was obtained for 88.2% of the subjects, while only 35.2% displayed a positive RAST to rLep d 2.6Cys. Conclusion: This study demonstrates that rLep d 2.6Cys is less able to evoke IgE-mediated reactions and cellular responses, as measured both in skin and in serum, than rLep d 2. In the future this hypoallergenic derivative may be a promising candidate molecule for immunotherapy of L. destructor-allergic patients.