f416 rTri a 19; Omega-5 Gliadin - a risk marker for severe immediate or exercise-induced reactions in patients with suspected wheat allergy

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f416 rTri a 19 Omega-5 Gliadin- a risk marker
for severe immediate or exercise-induced
reactions in patients with suspected wheat
allergy

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Classification of wheat proteins
Albumin
Water/salt soluble
Globulin
Wheat proteins
Gliadins (a-,ß-,?-,?-1,2,3,4, ?-5)
Water/salt insoluble
(Gluten 85)
Glutenins (HMW-, LMW-)
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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/saltinsoluble 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.

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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).

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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.

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Doctors diagnosis of wheat allergy and levels of
IgE ab to omega-5 gliadin in 88 children
sensitized to wheat
37/44 (84) gt 0.35 kUA/l
12/44 (27) gt 0.35 kUA/l
Reference Ito K et al. Poster presented at AAAAI
in San Diego 2007
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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
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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.

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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).
• 30-50 of patient with WDEIA are, however,
  negative with f4 Wheat ImmunoCAP, but a majority
  are positive to omega-5 gliadin.

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IgE ab to different wheat proteins in patients
with WDEIA
IgE ab to different wheat proteins in patients
with WDEIA
Peptide A Omega-5 gliadin Peptide B
HMW-glutinin
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Investigation of risk for severe immediate or
exercise-induced reactions in patients with
suspected wheat allergy
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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).
• 30-50 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.

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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

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Anamnesis

• Onset three years ago, June 2003.
• 15 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.

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What is the offending allergen (s)?
- ImmunoCAP
tested in South Africa

• 13 Nov 2003
• Total IgE 1601 kU/l
• Phadiatop positive
• Cat 1.09 kUA/l
• Mixed Cockroach 0.56 kUA/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 kUA/l
• Negative test results soy, peanut, wheat, fish,
  shrimp, cheese

• Negative lt 0.35 kUA/l

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What is the offending allergen (s)?
- ImmunoCAP tested in South Africa

• 11 March 2006
• Total IgE 2315 kU/l
• Mixed cockroach 0.81 kUA/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 lt 0.35 kUA/l

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What is the offending allergen (s)?
- ImmunoCAP tested at Phadia in Sweden

• Wheat 3.3 kUA/l
• Gluten 4.4 kUA/l
• Gliadin 30.5 kUA/l
• Omega-5 Gliadin 30.5 kUA/l
• Negative test results tomato, Gly m 4, Ara h
  8, onion, grape, mustard, alfa-lactalbumin,
  beta-lactoglobuline, CCD MUXF3
• Negative lt 0.1 kUA/l

• Fall 2006
• Phadiatop 0.47 PAU/l
• Pork 0.81 kUA/l
• Mushroom 0.1 kUA/l
• Sesame 0.19 kUA/l
• Black pepper 0.13 kUA/l
• Olive 0.15 kUA/l
• Casein 0.19 kUA/l
• Bovine lactoferrin 0.64 kUA/l
• Beef 1 kUA/l
• Anisakis 0.15 kUA/l
• Echinococcus 0.91 kUA/l

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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 kUA/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
  kUA/L) the wheat test was repeated and now found
  positive (3.3 kUA/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.

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Information material available
New Horizon 1/2007 article clinical leaflet,
product leaflet and test chart
See more info in Marketing Info No. 6 7/2007
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