Detection of Type I Hypersensitivity
المؤلف:
APURBA S. SASTRY , SANDHYA BHAT
المصدر:
Essentials Of Medical Microbiology 2021
الجزء والصفحة:
3rd edition , p196-197
2025-09-21
449
Skin Prick Test
Small amounts of suspected potential allergens are introduced at different skin sites either by intradermal injection or by superficial scratching.
- If a person is already sensitized to the allergen, a local wheal and flare response develops within 30 minutes at the inoculation sites (Fig. 1)
- Advantage: Skin test is relatively inexpensive and allows screening of a large number of allergens at one go
- Disadvantage: It may occasionally sensitize the individual to new allergens and in some rare cases may in duce late-phase reaction or even systemic anaphylactic shock.
Fig1. Skin testing by intradermal testing of allergens into forearm.
Total Serum IgE Antibody
Quantitative detection of total serum IgE is performed by various formats such as enzyme immunoassay or radiometric assay called radioimmunosorbent test (RIST, now not in use).
Allergen-specific IgE
Detection of allergen-specific IgE is more specific than total IgE detection. Various test formats are available.
- Multiplex immunoblot assay: Uses a nitrocellulose strip coated with 54 allergens
- Fluoro-enzyme immunoassay (FEIA): Commercially available as ImmunoCAP assay
- Automated immunoassay system (Hytec 288 Plus system)
- Anti-CCD absorbent IgE assay: Detects IgE after ab sorbing (removing) the nonspecific anti-CCD IgE which are produced against the cross-reactive carbohydrate determinants (CCD) present on the allergens
- RAST: Earlier, a radiometric assay called RAST (Radioallergosorbent test) was in use.
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