ImmunoCAP Total IgE

Quantifying the total concentration of IgE with ImmunoCAP Total IgE results in the evaluation of IgE-mediated allergy

 

ImmunoCAP Total IgE is an in vitro test for quantitative measurement of the total amount of circulating IgE in human serum or plasma samples. IgE antibodies appear as a result of sensitization to allergens and measurement of circulating total IgE provides an aid in the clinical diagnosis of IgE-mediated allergic disorders. Elevated levels of circulating total IgE are usually seen in patients suffering from extrinsic asthma, hay fever or atopic eczema. 

Expected test values

The serum concentration of total IgE is age-related. It increases during childhood and, at about 10 years of age, serum total IgE reaches values that are maintained during adult life.

AgeGeometric
mean
(kU IgE/l)
+ 1 SD
(kU IgE/l)
AgeGeometric
mean
(kU IgE/l)
+ 1 SD
(kU IgE/l)
Weeks Years
 6  0.6  2.3  2  5.7  23
 Months  3  8.0  32
 3  1.0  4.1  4  10  40
 6  1.8  7.3  5  12  48
 9  2.6  10  6  14  56
 12  3.2  13  7  16  63
           8  18  71
 9  20  78
 10  22  85

Specimen collection and preparation

  • Serum and plasma (EDTA or heparin) samples from venous or capillary blood can be used
  • Collect blood samples using standard procedures
  • Keep specimens at room temperature (RT) for shipping purposes only
  • Store at 2–8 °C up to one week, otherwise store at –20 °C
  • Avoid repeated freezing and thawing

Important note

As in all diagnostic testing, a definitive clinical diagnosis should not be based solely on the results of a single test method. A diagnosis should be made by the physician after evaluation of all clinical and laboratory findings. 

Test principle

The technology is based on an extremely high total binding capacity, 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, still giving low non-specific binding.

The ImmunoCAP solid phase consists of a cellulose derivative enclosed in a capsule. The hydrophilic, highly branched polymer provides an ideal microenvironment for allergens, binding them irreversibly while maintaining their native structure.

The test is designed as a sandwich immunoassay. 

Anti-IgE, covalently coupled to the solid phase, reacts with the total IgE in the patient serum sample.
After washing, 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 fluorescence is directly proportional to the concentration of IgE in the serum sample.

Reference

Johansson S.G.O., Yman L. In Vitro Assays for Immunoglobulin E. Clin Rev Allergy 1988;6(2):93-139.