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Allergen components PowerPoint Presentation

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Description : This medical presentation titled ""Allergen components"" tells us how allergens derived from plant and animal sources consist of multiple distinct proteins. It also tells us how allergenicity is largely determined by protein stability with proteins that are easily denatured by heat or digestive enzymes generally resulting in tolerance or milder symptoms than stable proteins and persistence of allergic symptoms is associated with specific protein allergens.

Tags : Allergen components, allergens, plant, animal, proteins, allergenicity, digestive enzymes, tolerance, symptoms, allergic symptoms, Allergen Nomenclature, Panallergens, Pet allergens,

Published on : Apr 26, 2021 | Views : 2503 | Downloads : 0

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Slide 1-

Allergen components
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Basis of allergen components Allergens derived from plant and animal sources consist of multiple distinct proteins. Testing for specific IgE against whole allergen extracts can identify binding to one or more of these protein antigens but not which ones(s) Protein allergens from a single species may have homology (similar structures) with proteins from closely related or unrelated species leading to cross reactivity Allergenicity in large part determined by protein stability with proteins that are easily denatured by heat or digestive enzymes generally resulting in tolerance or milder symptoms than stable proteins Persistence of allergic symptoms is associated with specific protein allergens
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Why are allergen components important? Particularly for food allergic individuals allergen components are related to: Potential severity of an allergic reaction Persistence of the allergy past childhood Whether an individual may be able to tolerate the food they are allergic to if heated Whether an individual may react to other foods or other plant or animal-derived allergens
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Allergen Nomenclature First 3 letters of genus first letter of species Number usually representing order in which discovered Example Bet v 1 First allergen component discovered for Betula vericossa (Birch tree pollen).
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PR-10 protein, Bet v1 homologue A heat labile protein, cooked foods are often tolerated Often associated with local symptoms such as oral allergy syndrome (OAS) Often associated with allergic reactions to fruit and vegetables in northern Europe LTP (non-specific Lipid Transfer Protein, nsLTP) A protein stable to heat and digestion causing reactions also to cooked foods Often associated with systemic and more sever reactions in addition to OAS Often associated with allergic reactions to fruit and vegetables in southern Europe Profilin Seldom associated with clinical symptoms but may cause demonstrable or even severe reactions in a small minority of patients Storage Protein Protein found in seeds serving as source material during the growth of a new plant Often stable and heat-resistant proteins causing reactions also to cooked foods CCD (cross-reactive carbohydrate determinants) Seldom associated with clinical symptoms but may cause demonstrable or even severe reactions in a small minority of patients Lipocalcin Very stable proteins; allergen components displaying limited cross-reactivity between species Parvalbumin A major allergen in fish A marker for cross-reactivity among different species of fish and amphibians A protein stable to heat and digestion causing reactions also to cooked foods Serum albumin A common protein present in different species of fish and amphibians A protein stable to heat and digestion causing reactions also to cooked foods Tropomyosin An actin-binding protein in muscle fibers A marker for cross-reactivity between crustaceans, mites, and cockroaches Major Plant and Animal -Derived Protein Allergen Classes- Panallergens
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Major Animal-Derived Protein Allergen Classes- Panallergens
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Major Plant-Derived Protein Allergen Classes- Panallergens
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With case history of Hen’s Egg Allergy f1 Egg White Positive f233 Ovomucoid Component Negative Positive -mild egg allergy -confirmed egg allergy -will probably tolerate -Will not tolerate any egg cooked, baked egg.
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Ara h 2 – ImmunoCAP® f423 rAra h 2 Often associated with systemic and severe reactions. Associated with cross-reactivity to tree nuts, e.g. almond and brazil nut. A peanut storage protein. Ara h 1 – ImmunoCAP® f422 rAra h 1 Often associated with clinical reactions. Associated with cross-reactivity to nuts and legume seeds, e.g. lentil and pea. A peanut storage protein. Ara h 3 – ImmunoCAP® f424 rAra h 3 Often associated with clinical reactions. Associated with cross-reactivity to lupin and soybean. A peanut storage protein. Ara h 9 – ImmunoCAP® f427 rAra h 9 Often associated with systemic and more severe reactions in addition to Oral Allergy Syndrome (OAS).In peanut however, severe reactions to LTP are not well documented. Stable to heat and digestion, risk for reactions also to cooked food. A LTP (Lipid Transfer Protein). Ara h 8 – ImmunoCAP® f352 rAra h 8 Often associated with local reactions such as OAS. A marker for birch-pollen related cross-reactions to peanut. A heat labile protein, cooked food is often tolerated. A PR-10 protein. CCD – ImmunoCAP® Ro214 MUXF3 Rarely associated with clinical reactions. A marker for sensitization to cross-reactive carbohydrate determinants (CCD). Present in all plants.            References: Astier C et al. J Allergy Clin Immunol 2006;118:250, Flinterman AE et al. Clin Exp Allergy 2007;37:1221, Koppelman S.J et al. Clin Exp Allergy 2004;34:583, McDermott RA et al. Clin Exp Allergy 2007;37:752, Mittag D et al. J Allergy Clin Immunol 2004;114:1410, Peeters KA et al. Clin Exp Allergy 2007;37:108 Suspicion of peanut allergy Is it allergy? Risk for severe reactions?
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Pet allergens
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Potential representation of allergenic materials in SNOMED Organism Allergen Example allergen components 448169003 |Felis catus (organism)| Fel d1 Fel d2 (aka 412140006 |Cat serum albumin (substance)| 412140006 |Cat serum albumin (substance)| Cat sebaceous gland protein Cat urine protein 264401009 |Dermatophagoides pteronyssinus (organism)| 720687003 |Dust mite protein (substance)| Der p1 Source Dust mite feces 260152009 |Cat dander (substance)|
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Theoretical allergen hierarchies
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Important allergen components to consider Peanut Ara h1, 2, 3, 6, 8, 9 Milk Bos d 4 (Alpha-lactalbumin) Bos d 5 (Beta-lactoglobulin) Bos d 6 (Bovine serum albumin) Bos d 8 (Casein) Egg Ovomucoid (nGal d 1) fOvalbumin (nGal d 2) Conalbumin (nGal d 3) Lysozyme (nGal d 4) Cat Fel d 1 Fel d 2 Fel d 4 Dog Can f 1 Can f 2 Can f 5