Common names: MUXF3, carbohydrates, CCD, glycans
Biological function: Glycosylation of proteins brings better hydro-philicity and stronger resistance to thermic shocks
Cross-reactive Carbohydrate Determinant (CCD)
o214 Allergen component MUXF3 CCD, Bromelain
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:
- Sensitization to foods of plant origin, mainly vegetables and fruits, but could also be useful with seeds such as peanuts.
- Sensitization to Hevea latex in a pollen allergic patient without occupational risk factors.
- In subjects tested positive both for honeybee and for wasp venoms, or in subjects allergic to these venoms and tested positive for pollen.
Degranulation of mast cells require the binding of at least two epitopes to two adjacent IgE antibody molecules. This cross-linking may be achieved by two peptide epitopes, by one glycan and one peptide epitope, but also by two glycan epitopes.
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, email@example.com
Fötish K, Altmann F, Haustein D, Vieths S. Involvement of carbohydrate epitopes in the IgE response of celery-allergic patients.
Int Arch Allergy Immunol 1999;120:30-42
Fötish 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.
J Allergy Clin Immunol 2003;111,889-96
van Ree R. Carbohydrate epitopes and their relevance for the diagnosis and treatment of allergic diseases.
Int Arch Allergy Immunol 2002;129:189-97
van Ree R. Clinical importance of cross-reactivity in food allergy. Curr Opin Allergy Clin Immunol 2004;4:235-40
Vieths S, Scheurer S, Ballmer-Weber B. Current understanding of cross-reactivity of food allergens and pollen.
Ann N Y Acad Sci 2002;964:47-68
Mairesse M, Ledent C. Allergie aux venins d’hyménoptères: intérêt du dosage des IgE anti-broméline.
Rev Fr Allergol Immunol Clin 2003;43:95
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