Components

  1. What is the new Gliadin (f98) composed of?

    Gliadin (f98) contains native, highly purified (99%) alpha-, beta-, gamma- and omgega-gliadins (including omega-5 gliadin) and this product shows high sensitivity for detecting gliadin-specific IgE antibodies. It does not pick up any grass cross-reacting IgE antibodies. Comment: In the 1% that is not gliadins, there is no profilin, CCD or LTP. Profilin and CCD are the allergens responsible for cross-reactivity with grass.

  2. What is the utility of f98?

    Gliadins are specific markers for IgE mediated wheat food allergies and a severity marker in immediate wheat allergy and Wheat-Dependent Exercise-Induced Allergy (WDEIA).

  3. Will f98 replace any existing product, e.g. gluten (f79)?

    No, not at this point.

  4. What is gluten (f79) good for? Why is gluten (f79) not included in the Wheat Sales Package?

    The gluten ImmunoCAP (f79) contains many water soluble, grass-cross-reactive proteins and is furthermore rather low in glutenins and gliadins. Therefore this is not really a good test. <strong>Comment:</strong> The likelihood that sensitization to e.g. HMW can be picked up by f79 has not been evaluated, but is considered to be low.

  5. Can f98 be used for diagnosing celiac disease?

    f98 has been developed for the detection of IgE antibodies in wheat food allergy. It is not intended for and has not been validated for IgA and IgG antibody diagnostic testing in celiac disease, i.e. no cut off value has been established.

  6. Do we have any deamidated gliadin/hydrolyzed gliadin for IgE measurements?

    No. The only deamidated gliadin product is the EliA Gliadin DP which is intended for IgA/IgG detection in sera of patients suspected of celiac disease.

  7. What is the composition of Gliadin IgA/IgG ImmunoCAP (AGf98) ?

    Gliadin AGf98 contains a purified Gliadin preparation and is intended for detecting IgA/IgG in celiac disease patients. It is not intended for detecting sIgE against gliadins, and it gives a high background signal in the range 0.1-1 kU<sub>A</sub>/L, furthermore it contains some water-soluble proteins that pick up non-gliadin directed sIgE.

  8. What weat products are available at the moment?

    <strong>List of ImmunoCAP wheat products</strong> <strong><span style="text-decoration: underline;">IgE detection</span></strong> Wheat (f4) Gliadin (f98) Tri a 19, w-5 gliadin, (f416) Tri a 14, LTP (f433) Gluten (f79) &nbsp; <strong><span style="text-decoration: underline;">IgA/IgG detection</span></strong> Gliadin IgA/IgG ImmunoCAP (AGf98)

  9. Why should omega-5 gliadin (f416) be used together with Gliadin (f98)?

    While Gliadin (f98) has a high sensitivity for detecting sensitization to gliadins, the specificity of w-5 gliadin (f416) is higher. Available data – published and preliminary – indicate that by combined testing for gliadin- and w-5 gliadin-specific antibodies most patients with immediate type wheat allergy, and WDEIA – see Hofmann et al. 2013., can be identified. <img style="vertical-align: middle; border: black 2px solid;" src="/FAQ/Allergy/Specific%20IgE/Components/Wheat%20CAP%20testing.png" alt="" width="500" height="247" /> The majority of patients with wheat symptoms are sensitized to both gliadin and omega-5 gliadin. &nbsp;

  10. How cross-reactive to other LTPs is the wheat LTP Tri a 14?

    The sequence homology between Pru p 3 (peach LTP) and Tri a 14, is rather low - in the range of 45%. There is little information in the published literature on the degree of cross-reactivity, and concerning the clinical cross-reactivity this is even less documented. The conclusion is that we cannot say much about this, more than that LTP cross-reactivity may occur.

  11. What other wheat allergen components may be of importance in wheat allergy?

    Other wheat allergen components described in the literature are High and Low molecular weight glutenins (HMW and LMW, respectively) that are implicated in both immediate wheat allergy and WDEIA. However, most patients seem to be sensitized to several gluten derived proteins, and mono-sensitization to LMW or HMW is probably of low prevalence.

  12. How do the wheat extract (f4), gluten (f79) and the existing Gliadin (AGf98) ImmunoCAP compare in terms of what sensitizations they detect?

    AGf98 was developed for and is intended only for IgA and IgG measurements in celiac disease, however some literature data on its (off-label) use for measuring IgE is available. In-house as well as published data show that when used to detect IgE antibodies f4, f79 and AGf98 give similar qualitative results – they pick up more or less the same sensitizations. All three products contain many water/salt soluble wheat proteins and in addition differing amounts of gliadins and are thus of rather low specificity for detecting specific wheat allergy (i.e. they also pick up grass-cross reacting IgE antibodies).

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.