Immuno Solid-phase Allergen Chip (ISAC)

Immunology

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Description

Specific IgE tests usually contain a crude mixture of the allergen, including allergen specific and potentially cross-reactive components. ISAC ( Immuno Solid-phase allergen Chip ) allows >100 individual allergen specific components to be assayed simultaneously. It includes marker allergens/component groups ( eg. PR-10, LTP ) that can be used to determine the genuine cause of sensitisation. Results generated are semi-quantitative. Common component groups: � PR10 proteins share similar structures to Bet v 1 which is the major allergen in birch pollen. Sensitisation to PR10 usually results in localised oral allergy syndrome symptoms and multiple positive specific IgE tests/skin prick tests. � Lipid transfer proteins ( LTPs ) are usually associated with more systemic reactions as the proteins are heat and protease labile, therefore a positive LTP result is usually due to true sensitisation rather than cross-reactivity. However some LTPs can be non-specific. � Profilins are related to Bet v 2 which is the minor birch pollen allergen ( also in grass as phl p 12 ). Generally not associated with clinical symptoms but can be the cause of multiple positive specific IgE tests/skin prick tests. � Tropomyosin is the cross reactive component associated with crustacian, mite, cockroach sensitivity. This test is particularly useful in complicated allergy cases which may be due to a single sensitising agent cross-reacting with others, or multiple sensitisations. ISAC utilises component resolved diagnostics to aid in determining the cause of sensitisation and if it is likely to be cross-reactive.

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Indications

Complex allergy cases, such as: polysensitised patients, patients not responding to satisfactorily to treatment, and in cases with inconsistent history.

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Sample Type

2mL Serum ( Gel 5mL Yellow tube ). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

See report for interpretation of results.

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Turnaround Time

Within 1 week

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Testing Frequency

Weekly

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External Notes

Please supply relevant clinical history and results of Specific IgE and skin prick test to aid interpretation of the results.

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References

Hansen K S, Poulsen L K. Component Resolved Testing for Allergic Sensitization. Curr Allergy Asthma Rep. 2010. 10:340-348.Ott H, et al. Clinical usefulness of microarray-based IgE detection in children with suspected food allergy. Allergy. 2008. 63( 11 ):1521-1528.Wohrl S, et al. The performance of a component-based allergen-microarray in clinical practice. Allergy. 2006. 61( 5 ):633-639.

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See Also

Specific IgE, Total IgE

Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.