ara h1 and ara h2 Two of these things belong together, two of these things are kinda

Posted on: Mon, 04/12/2004 - 9:42pm
MommaBear's picture
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Joined: 09/23/2002 - 09:00

the same................ [img]http://uumor.pair.com/nutalle2/peanutallergy/biggrin.gif[/img]

seems these two siblings are the more often discussed.

Threads discussing certain qualities of ara h1:

[url="http://uumor.pair.com/nutalle2/peanutallergy/Forum1/HTML/003519.html"]http://uumor.pair.com/nutalle2/peanutallergy/Forum1/HTML/003519.html[/url]

[url="http://uumor.pair.com/nutalle2/peanutallergy/Forum8/HTML/000747.html"]http://uumor.pair.com/nutalle2/peanutallergy/Forum8/HTML/000747.html[/url]

does anyone have similiar items discussing ara h2?

Posted on: Thu, 04/15/2004 - 12:01am
Lovey's picture
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Joined: 03/22/2004 - 09:00

[url="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15080811&itool=iconabstr"]http://www.ncbi.nlm.nih.gov/entrez/query...itool=iconabstr[/url]
Relevance of Ara h1, Ara h2 and Ara h3 in peanut-allergic patients, as determined by immunoglobulin E Western blotting, basophil-histamine release and intracutaneous testing: Ara h2 is the most important peanut allergen.
Koppelman SJ, Wensing M, Ertmann M, Knulst AC, Knol EF.
TNO Nutrition and Food Research, Zeist, The Netherlands.
Summary Background A number of allergenic proteins in peanut has been described and the relative importance of these allergens is yet to be determined. Objectives We have investigated the relevance of previously identified peanut allergens in well-characterized peanut-allergic patients by in vitro, ex vivo and in vivo assays. Methods Thirty-two adult peanut-allergic patients were included based on careful and standardized patient history and the presence of peanut-specific IgE. The diagnosis peanut allergy was confirmed using double-blind placebo-controlled food challenges in 23 patients. Major peanut allergens Ara h1, Ara h2 and Ara h3 were purified from peanuts using ion-exchange chromatography. IgE immunoblotting was performed and IgE-cross-linking capacity was examined by measuring histamine release (HR) after incubating patient basophils as well as passively sensitized basophils with several dilutions of the allergens. Intracutaneous tests (ICTs) using 10-fold dilution steps of the purified allergens and crude peanut extract were performed. Results Ara h2 was recognized most frequently (26 out of 32) in all tests and induced both positive skin tests and basophil degranulation at low concentrations, whereas Ara h1 and Ara h3 were recognized less frequently and reacted only at 100-fold higher concentrations as analysed with HR and intracutaneous testing (ICT). Next to the three tested allergens, proteins with molecular weights of somewhat smaller than 15 kDa were identified as a IgE-binding proteins on immunoblot in the majority of the patients (20 out of 32). Conclusion We conclude that Ara h2 is, for our patient group, the most important peanut allergen, and that previously unidentified peanut proteins with molecular weights of somewhat smaller than 15 kDa may be important allergens as well. ICT in combination with basophil-HR and IgE immunoblotting provides insight in the patient specificity towards the individual peanut allergens.
PMID: 15080811 [PubMed - in process]

Posted on: Thu, 04/15/2004 - 2:26am
MommaBear's picture
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Joined: 09/23/2002 - 09:00

Does ara h2 hang around as long as ara h1. Or ara h3?
Do reactions caused by ara h2 differ from those caused by ara h1 or ara h3?

Posted on: Mon, 04/19/2004 - 11:48am
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Joined: 05/13/2003 - 09:00

[url="http://www.blackwell-synergy.com/links/doi/10.1111/j.1365-2222.2004.1923.x/full/"]http://www.blackwell-synergy.com/links/doi/10.1111/j.1365-2222.2004.1923.x/full/[/url]
Relevance of Ara h1, Ara h2 and Ara h3 in peanut-allergic patients, as determined by immunoglobulin E Western blotting, basophil-histamine release and intracutaneous testing: Ara h2 is the most important peanut allergen
S.J. Koppelman * , M. Wensing , M. Ertmann , A.C. Knulst and E.F. Knol
Summary
Background A number of allergenic proteins in peanut has been described and the relative importance of these allergens is yet to be determined.
Objectives We have investigated the relevance of previously identified peanut allergens in well-characterized peanut-allergic patients by in vitro, ex vivo and in vivo assays.
Methods Thirty-two adult peanut-allergic patients were included based on careful and standardized patient history and the presence of peanut-specific IgE. The diagnosis peanut allergy was confirmed using double-blind placebo-controlled food challenges in 23 patients. Major peanut allergens Ara h1, Ara h2 and Ara h3 were purified from peanuts using ion-exchange chromatography. IgE immunoblotting was performed and IgE-cross-linking capacity was examined by measuring histamine release (HR) after incubating patient basophils as well as passively sensitized basophils with several dilutions of the allergens. Intracutaneous tests (ICTs) using 10-fold dilution steps of the purified allergens and crude peanut extract were performed.
Results Ara h2 was recognized most frequently (26 out of 32) in all tests and induced both positive skin tests and basophil degranulation at low concentrations, whereas Ara h1 and Ara h3 were recognized less frequently and reacted only at 100-fold higher concentrations as analysed with HR and intracutaneous testing (ICT). Next to the three tested allergens, proteins with molecular weights of somewhat smaller than 15 kDa were identified as a IgE-binding proteins on immunoblot in the majority of the patients (20 out of 32).
Conclusion We conclude that Ara h2 is, for our patient group, the most important peanut allergen, and that previously unidentified peanut proteins with molecular weights of somewhat smaller than 15 kDa may be important allergens as well. ICT in combination with basophil-HR and IgE immunoblotting provides insight in the patient specificity towards the individual peanut allergens.
Introduction Go to: Choose Top of page Introduction << Methods Results Discussion Acknowledgements References
Peanut allergy is one of the most severe food allergies due to its persistency and the life-threatening character [1]. The prevalence of peanut allergy in the United Kingdom is estimated to be about 0.5% [2] and in the USA, the prevalence of peanut and tree nut allergy is 1.1% [3], representing a main health concern. Doses as low as 100 g of peanut protein may already provoke symptoms [4, 5], indicating that accidental ingestion of minute traces of peanut can endanger the life of peanut-allergic patients. The nature of the allergenic compounds in peanuts has been studied extensively in the last decade. Ara h1 was identified as a major peanut allergen [6, 7] and has gained a considerable amount of attention in recent years. Ara h1 was purified and characterized on a molecular level. It appears to be a 63 kDa glycoprotein, with isoforms having different isoelectric points [8], that is present in peanut as a trimer [9, 10]. The amino acid sequence of Ara h1 [11] was elucidated after cloning the gene. Subsequently, synthetic peptides based on this sequence were synthesized and 23 IgE-binding epitopes were mapped [12]. However, the recombinant Ara h1 appeared to contain a 86 amino acid N-terminal sequence that is not found in Ara h1 purified from peanuts [7]. Interestingly, this sequence contained two immunodominant IgE epitopes [12]. Ara h2 was identified as a second important peanut allergen, although the relative importance of Ara h2 compared with Ara h1 is disputed [7, 13, 14]. Cloning techniques have revealed the complete amino acid sequence of Ara h2 [15]. Ara h3 was in first instance identified by Eigenmann et al. [16] as a 14 kDa peanut protein, but cloning its gene revealed a protein of approximately 60 kDa identified as peanut glycinin with IgE-binding sites throughout the gene product [17]. Meanwhile, Kleber-Janke described an identical peanut allergen, and confusingly the official name given by the IUIS Allergen Nomenclature Sub-Committee was Ara h4. The differences in molecular weight described for Ara h3 suggest that the gene product in peanut is stored in a processed form, as is the case for Ara h1. Another aspect that hampers the research of peanut allergens is that a number of different polypeptides are derived from one gene product. This results in a set of proteins with probably different molecular characteristics that are referred to only one name. For example, Ara h3 purified from peanut consists of a set of polypeptides with molecular weights ranging from 14 to 45 kDa [18].
The gold standard in diagnostics of food allergy is the double-blind placebo-controlled food challenge (DBPCFC). However, this test is expensive and laborious and patient safety can be a dilemma. Several in vitro, ex vivo and in vivo diagnostics tests can be performed to address the implication of IgE-peanut-allergen interactions. In patient serum CAP/RAST or ELISA can demonstrate IgE antibodies specific for an allergen, assays in which the allergen is coupled to a solid phase. By immunoblotting allergens are separated on basis of their molecular weight and subsequently tested for their IgE-binding properties. Functional IgE-binding tests that also take into account the cross-linking of the IgE receptor are basophil degranulation assays and skin prick or intracutaneous tests (ICTs).
The aim of the current study was to assess the relevance of the peanut-derived purified allergens Ara h1, Ara h2 and Ara h3 by immunoblotting, histamine release (HR) assays and skin tests for 32 well-characterized adult peanut-allergic patients.
Methods Go to: Choose Top of page Introduction Methods << Results Discussion Acknowledgements References
Peanut protein extraction
Peanuts (Arachis hypogea) from the Runner cultivar (Cargill, Dawson, GA, USA) were generously provided by Imko Nut Products (Doetinchem, the Netherlands) and were stored at 10

Posted on: Mon, 04/19/2004 - 1:26pm
MommaBear's picture
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Joined: 09/23/2002 - 09:00

Thank you for posting the articles (everyone). I will read them closely tomorrow to better understand these items. Still wondering about those few questions I posted earlier. Any thoughts? Maybe it's in this literature.

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