Cloning and sequencing of a cDNA expressing a recombinant house dust mite protein that binds human IgE and corresponds to an important low molecular weight allergen.

Background: In tropical climates, sensitization to Bloma tropicalis and Dermatophagoides pteronyssinus is high and mainly directed to species–specific allergens. There is some cross–reactivity between extracts of these mites, probably due to the group 5 allergens that have high sequence homology. Objective and Methods: We used the radioallergosorbent test (RAST), RAST inhibition and immunoblotting inhibition experiments to investigate the cross–reactivity between the recombinant allergens BtM and Der p 5, expressed as glutathione S–transferase fusion proteins, to detect the epitopes involved and to analyze the importance of this cross–reactivity. Results: Seventy–nine percent of 48 patients sera were RAST positive to both recombinants, with a strong correlation (r = 0.8, p<0.0001). BtM inhibited 25 and 21.1% of IgE–binding to B. tropicalis and D. pteronyssinus extracts respectively and Der p 5 inhibited 22 and 24% of IgE–binding to D. pteronyssinus and B. tropicalis extracts. Furthermore, BtM inhibited 74.5% of IgE binding to Der p 5 and Der p 5 inhibited 72.4% of IgE–binding to BtM. RAST inhibition with BtM–derived synthetic peptides showed that peptide 4 (residues 35–50) and peptide 5 (residues 46–61) inhibited 37 and 16% of IgE–binding to BtM while peptides 5 and 2 (residues 14–30) were able to inhibit the IgE binding (32 and 28%, respectively) to Der p 5. Conclusion: There is cross–reactivity between BtM and Der p 5, which explains almost all the cross–reactivity between the two mite extracts. This cross–reactivity seems to be related to epitope(s) at the C–terminal segment of these allergens.

Section: Discussionmentioning

confidence: 92%

Analysis of the Cross–Reactivity between BtM and Der p 5, Two Group 5 Recombinant Allergens from Blomia tropicalis and Dermatophagoides pteronyssinus

Caraballo

Mercado²,

Jiménez³

et al. 1998

“…Subsequent studies with Der p 4 affinity purified with cyclodextrin showed 80% binding but the binding was extremely low and IgE from less than 40% of subjects bound IgE at >2 ng/ml [36]. The group 5 and 7 allergens react with IgE in 50% of sera often with a magnitude as high as the major allergens [37, 38, 39]. Der p 8 has been reported to bind IgE in 50% of sera from allergic subjects but quantitative studies have not been performed [40].…”

Section: Ige Binding To Purified Allergensmentioning

confidence: 99%

“…Der p 5 was identified from a partial cDNA clone which produced a polypeptide reactive with IgE in 40% of allergic sera [39]. The sequence encoded a 17,000 MW polypeptide with no N-glycosylation sites or cysteines, but IgE antibody affinity purified from the recombinant protein reacted with a 14,000 MW band in mite extracts.…”

Section: Group 5 Allergensmentioning

confidence: 99%

Characterization and Immunobiology of House Dust Mite Allergens

Thomas¹,

Smith²,

Hales³

et al. 2002

304

254

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 do not seem to have specific biological functions explaining their allergenicity, but it is demonstrated more and more that biological activity of allergens may promote the immunological conditions necessary for specific sensitization towards allergens. The best–analyzed example in this context is Der p 1, the major allergen of mites known to be a cysteine protease [17]. It was shown to augment its own permeability in the bronchial epithelium by proteolytic activity [29].…”

Section: Influence Of Functional Properties Of Allergensmentioning

confidence: 99%

The Biological Function of Allergens: Relevant for the Induction of Allergic Diseases?

Bufe

1998

During the last 10 years an increasing number of allergens were identified and biochemically as well as immunologically characterized. More and more information on the primary structure of these molecules, revealed by recombinant technologies, became available. Furthermore for several allergens the biological functions could be elucidated. Most recently it was shown that beside IgE–binding capacity functional properties such as enzyme activity may contribute to the allergenicity and the induction of allergic inflammation. These findings could stimulate novel concepts in allergy prevention and therapy. This review summarizes recent data in this area.