Presentation on theme: "1 2007-03-29 f416 rTri a 19; Omega-5 Gliadin - a risk marker for severe immediate or exercise-induced reactions in patients with suspected wheat allergy."— Presentation transcript:
f416 rTri a 19; Omega-5 Gliadin - a risk marker for severe immediate or exercise-induced reactions in patients with suspected wheat allergy
What is on ImmunoCAP ® f416 rTri a 19; Omega-5 Gliadin? Tri a 19; Omega-5 Gliadin from wheat ( Triticum aestivum). Omega-5 gliadin is a storage protein and a major allergen among water/salt–insoluble proteins, with limited presence on f4 Wheat ImmunoCAP. Omega-5 gliadin can be found to some extent on f79 Gluten and to a higher extent on f98 Gliadin ImmunoCAP. The immunodominant peptide epitopes of omega-5 gliadin have been identified. A cDNA encoding a hydrophilic portion of Tri a 19, containing major epitopes for IgE antibodies, has been cloned and expressed in E. coli and the purified recombinant product coupled to ImmunoCAP.
Possible clinical utility of ImmunoCAP ® f416 rTri a 19; Omega-5 Gliadin Identify patients at risk of developing severe immediate reactions to wheat. Identify patient at risk of developing anaphylaxis to wheat in relation to exercise (WDEIA).
Severe immediate reactions to wheat Are important to identify, especially in children. ~ 80% of patients with severe immediate reactions have IgE antibodies to both omega-5 gliadin and wheat. The remaining 20% of patients have IgE antibodies to other components in wheat and will thus be positive with f4 Wheat ImmunoCAP.
Doctors diagnosis of wheat allergy and levels of IgE ab to omega-5 gliadin in 88 children sensitized to wheat No wheat allergy n = 44 Wheat allergy n = 44 k U / L A Reference: Ito K et al. Poster presented at AAAAI in San Diego /44 (27%) > 0.35 kU A /l 37/44 (84%) > 0.35 kU A /l
Challenge outcome and levels of IgE ab to omega-5 gliadin in children sensitized to wheat Reference: Ito K et al. Poster presented at AAAAI in San Diego 2007
Wheat-dependent, exercise- induced anaphylaxis (WDEIA) Wheat allergy induced by physical exercise. Symptoms are typically generalized urticaria and severe allergic reactions such as anaphylactic shock or hypotension. Skin tests and in vitro IgE ab tests for wheat are not always satisfactory. Challenge test + intense physical exercise is the gold std for diagnosis, but is inconvenient and dangerous.
Major allergens in WDEIA ~80% of patients with WDEIA have IgE ab to omega-5 gliadin. ~20% of patients with WDEIA have IgE ab to high molecular weight glutenin (HMW-glutinin) % of patient with WDEIA are, however, negative with f4 Wheat ImmunoCAP, but a majority are positive to omega-5 gliadin.
IgE ab to different wheat proteins in patients with WDEIA Peptide A = Omega-5 gliadin Peptide B = HMW-glutinin
Investigation of risk for severe immediate or exercise- induced reactions in patients with suspected wheat allergy NoYes Test results f4 neg / f416 pos Test results f4 pos / f416 pos Test results f4 pos / f416 neg Test results f4 neg / f416 neg Test with ImmunoCAP Allergen: ™ f4 Wheat + f416 rTri a 19; Omega-5 Gliadin Conclusion No sensitization to wheat; symptoms are probably caused by another food or due to a different mechanism Conclusion High risk for severe immediate or exercise-induced reactions due to wheat Conclusion High risk for severe immediate reactions due to wheat Conclusion High risk for exercise- induced reactions due to wheat Conclusion Low risk for severe immediate or exercise-induced reactions due to wheat Is there a history of exercise-induced symptoms?
Recommended test procedure in patients with suspected wheat allergy f4 Wheat + f415 rTri a 19; Omega-5 gliadin The clinical relevance of a positive f4 Wheat test are sometimes difficult to interpret. Omega-5 gliadin is found to be a risk marker for severe immediate reactions including WDEIA (80% pos) % of patients with WDEIA have no IgE abs to wheat (f4). f4 neg & f416 neg tests: no sensitization to wheat is found; another food or mechanism is probably the cause. f4 neg & f416 pos tests: high risk for severe immediate reactions including WDEIA due to wheat. f4 pos & f416 pos tests: high risk for severe immediate reactions including WDEIA due to wheat. f4 pos & f416 neg tests: low risk for severe immediate reactions including WDEIA due to wheat. However, many of these patients will have immediate type reactions such as skin and gastrointestinal symptoms.
A case report Age: 57 Gender: Male Race group: White Country of birth: Zambia Living in: South Africa Occupation: Engineer, Project Manager (often very stressful) Activities: Camping, Cycling, Scuba diving, Hiking
Anamnesis Onset three years ago, June adverse reactions between June -03 and Feb -06. Reaction one hour after eating with extreme itching from hairline to armpits, buttocks and groin where hives break out. Steadily increasing hart rate (180 beats vs. 80 normally). Tight chest with labored breathing. Loss of conscious ones with cardiac arrest. Mild reactions on a few occasions that were stopped with 3 antihistamine tablets. Many hospital visits with intravenous adrenaline and cortisone.
What is the offending allergen (s)? - ImmunoCAP ® tested in South Africa 13 Nov 2003 Total IgE 1601 kU/l Phadiatop positive Cat 1.09 kU A /l Mixed Cockroach 0.56 kU A /l Negative test results*: Dog, mites, trees, weeds, timothy grass, mould, egg, milk, soy, peanut, wheat, fish and shrimp 31 March 2004 Total IgE 1818 kU/l Phadiatop positive Milk 0.58 kU A /l Negative test results*: soy, peanut, wheat, fish, shrimp, cheese * Negative < 0.35 kU A /l
What is the offending allergen (s)? - ImmunoCAP ® tested in South Africa 11 March 2006 Total IgE 2315 kU/l Mixed cockroach 0.81 kU A /l (tropomyosin) Avocado & pear negative* (Chitinase) Pineapple negative* (Profilin) Sunflower seed negative* (2S albumin) Peach negative* (LTP) Strawberry negative* (Bet v 1) Salmon negative* (Calcium binding protein/Polcalcin) Yeast negative* (Enolase) Bell pepper/paprika negative* (Thaumatin protein) * Negative < 0.35 kU A /l
What is the offending allergen (s)? - ImmunoCAP ® tested at Phadia in Sweden Fall 2006 Phadiatop 0.47 PAU/l Pork 0.81 kU A /l Mushroom 0.1 kU A /l Sesame 0.19 kU A /l Black pepper 0.13 kU A /l Olive 0.15 kU A /l Casein 0.19 kU A /l Bovine lactoferrin 0.64 kU A /l Beef 1 kU A /l Anisakis 0.15 kU A /l Echinococcus 0.91 kU A /l Wheat 3.3 kU A /l Gluten 4.4 kU A /l Gliadin 30.5 kU A /l Omega-5 Gliadin 30.5 kU A /l Negative test results*: tomato, Gly m 4, Ara h 8, onion, grape, mustard, alfa-lactalbumin, beta-lactoglobuline, CCD; MUXF3 * Negative < 0.1 kU A /l
Summary case report Omega-5 gliadin from wheat was finally found to be the offending allergen. Since wheat was tested negative already in South Africa it was not at once retested at Phadia. To test for gluten (f79) was a last try to find the offending allergen. The positive gluten result (4.4 kU A /L) led into testing with gliadin (AGf98) but also omega-5 gliadin (f416) that was under development. When omega-5 gliadin was tested positive (30.5 kU A /L) the wheat test was repeated and now found positive (3.3 kU A /L). Similar levels of IgE ab to gliadin (AGf98) and omega-5 gliadin (f416), indicate that the amount of omega-5 gliadin is fairly good represented on gliadin ImmunoCAP AGf98.
Information material available See more info in Marketing Info No. 6 & 7/2007 New Horizon 1/2007; article & clinical leaflet, product leaflet and test chart
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