The ImmunoCAP® Specific IgE blood tests are in vitro quantitative assays for the measurement of allergen-specific antibodies in human serum or plasma. They are intended for in vitro diagnostic use as an aid in the clinical diagnosis of antibody-mediated allergic disorders in conjunction with other clinical findings, and can be used in clinical laboratories, as well as physician office laboratories.
The test is designed as a sandwich immunoassay(a method using two antibodies, which bind to different sites on the antigen or ligand). The basis of the innovative ImmunoCAP technology is the 3 dimensional cellulose sponge matrix. It consists of a cellulose derivative enclosed in a capsule. This unique reaction environment allows for the binding of clinically relevant allergens, even those present at very low levels. The hydrophilic, highly branched polymer provides an ideal microenvironment for allergens, binding them irreversibly while maintaining their native structure. This extremely high overall binding capacity is achieved through a high binding capacity per mg cellulose in combination with an optimal amount of cellulose in each solid phase. This ensures binding of all relevant antibodies, regardless of antibody affinity, while still giving low non-specific binding. This provides high sensitivity so that very low concentrations of allergen-specific IgE antibodies can be detected.
|The allergen of interest, covalently coupled to the ImmunoCAP, reacts with the specific IgE in the patient sample.|
|After washing away non-specific IgE, enzyme-labelled antibodies against IgE are added to form a complex.
|After incubation, unbound enzyme-labelled anti-IgE is washed away and the bound complex is then incubated with a developing agent.
|After stopping the reaction, the fluorescence of the eluate is measured. The higher the fluorescence, the more specific IgE is present in the sample. To evaluate test results, the responses of patient samples are compared directly to the responses of calibrators.|
The calibrators are directly traceable to the WHO International Reference Preparation for human IgE 75/502. Measured response values for allergen specific IgE antibodies are evaluated against a Total IgE calibration curve and expressed as concentration of Allergen specific Units (kUA/l).
Currently, there is no established international reference preparation for allergen specific IgE antibodies. For total IgE protein a mass Unit (U) is defined by the World Health Organization (WHO) International Reference Preparation 75/502. 1 IU has been shown to be equal to 2.42 ng IgE protein. ImmunoCAP Specific IgE detects IgE antibodies in serum in the range of 0.1-100 kUA/l.
U = international unit for IgE as defined by WHO International Reference 75/502
UA = allergen specific unit
All Information provided by Phadia. ImmunoCAP is a registered trademark of Phadia.