How can I use the IgE ISU level information?
Answer: It may hold information regarding the primary/dominating sensitizing allergen.
Example: A grass pollen allergic patient is tested on ISAC.
Results: Bermuda grass Cyn d 1 = 78 ISU and Timothy grass Phl p 1 = 6 ISU.
Explanation: ISAC is a semi-quantitative technology, providing useful ISAC ISU levels. The relative ISU levels provide strong indicators and ISAC gives similar IgE ab levels as detected by the ImmunoCAP technology . The ISU (ISAC Standard Units) are also calibrated against the ImmunoCAP kU/l in the measurement range 0.3 – 100 ISU. For patients with many IgE responses within the same/similar protein family, the response level indicates the original/dominating sensitizer. In this example Bermuda grass is likely the original sensitizer while Phl p 1 gives an IgE response due to cross-reactivity.
Another example on the same topic:
Background: A patient with suspicion of peanut and tree nut allergy is tested on ISAC.
Results: Hazelnut Cor a 9 = 76 ISU, peanut Ara h 2 = 0.7 ISU, Ara h 3 = 1.6 ISU and soy Gly m 6 = 18 ISU.
Explanation: In this example hazelnut is likely the original sensitizer, giving rise to cross-reactivity to both soy and peanut (with or without clinical manifestation).
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