ImmunoCAP250 FEIA
Many allergens are glycoproteins, i.e. they contain one or several complex oligosaccharide chains linked to the peptide structure of the protein. Studying the structure of allergens and their IgE antibody binding epitopes several research groups have searched for a role of the carbohydrate moieties of allergenic molecules. Since glyco-epitopes can share significant structural homologies beyond the limits of protein families they are prone to extensive cross-reactivity and they have been called Cross-reactive Carbohydrate Determinants or CCDs.
Whether or not IgE antibodies against carbohydrate epitopes on glycoproteins have a clinical role is debated, but data supporting a clinical effect are emerging. As long as the demonstration of a clear in vivo effect remains to be confirmed, we must consider the sometimes confusing role of these epitopes in serum-based IgE antibody assays.
Testing for CCD-specific IgE reactivity
A CCD test could be useful when in vitro results do not match the clinical picture (symptoms, skin tests), especially when numerous results are found positive without obvious clinical symtoms to all these allergens. Checking the possible presence of anti-CCD IgE is advisable in three types of situations:
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Sensitization to foods of plant origin, mainly vegetables and fruits, but could also be useful with seeds such as peanuts.
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Sensitization to Hevea latex in a pollen allergic patient without occupational risk factors.
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In subjects tested positive both for honeybee and for wasp venoms, or in subjects allergic to these venoms and tested positive for pollen.
Allergen description
Bromelain (Ana c 1) is a glycoprotein extracted from pineapple, Ananas comosus. Bromelain has widely been used for checking the cross-reactivity between a glycan and other glycoproteins since its MUXF3 carbohydrate chain is found in many plant proteins. True allergy to bromelin is also very rare.
ImmunoCAP Allergen o214 Allergen component MUXF3 CCD, Bromelain, is a pure CCD reagent containing only the MUXF3 carbohydrate epitope, thus avoiding IgE antibody binding to other bromelain epitopes. The MUXF3 carbohydrate epitope is purified from digested bromelain.
Compiled by Dr Harris Steinman, harris@zingsolutions.com
1.
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2.
Fotish K, Westphal S, Lauer I, Retzek M, Altmann F, Kolarich D, Scheurer S, Vieths S. Biological activity of IgE specific for cross-reactive carbohydrate determinants.
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3.
van Ree R. Carbohydrate epitopes and their relevance for the diagnosis and treatment of allergic diseases.
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4. van Ree R. Clinical importance of cross-reactivity in food allergy. Curr Opin Allergy Clin Immunol 2004;4:235-40
5.
Vieths S, Scheurer S, Ballmer-Weber B. Current understanding of cross-reactivity of food allergens and pollen.
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6.
Mairesse M, Ledent C. Allergie aux venins d'hymenopteres: interet du dosage des IgE anti-bromeline.
Rev Fr Allergol Immunol Clin 2003;43:95
7.
Kochuyt AM, Van Hoeyveld EM, Stevens EA. Prevalence and clinical relevance of specific immunoglobulin E to pollen caused by sting-induced specific immunoglobulin E to cross-reacting carbohydrate determinants.
Clin Exp Allergy 2005; 35:441-7
This information is from the Phadia website, copyright Thermofisher.
For further information contact the laboratory (09) 307 4949 ext 22000 or:
Associate Professor Rohan Ameratunga , Immunopathologist: Locator 93-5724
Or the LabPLUS Immunology Team