ImmunoCAP Specific IgA

Quantifying antigen-specific IgA antibodies with ImmunoCAP Specific IgA results in accurate evaluation of allergy patients


ImmunoCAP Specific IgA measures antigen-specific IgA antibodies in human serum and plasma. Specific IgA antibodies are part of the body’s immune system. They are present in secretions such as saliva and mucosa, as well as in the blood. High levels of specific IgA antibodies in serum to food antigens may indicate increased exposure caused by damage to the intestinal mucosa. In celiac disease, for example, the levels of specific IgA antibodies to gliadin are important for diagnosis. Monitoring elevated levels of antigen-specific IgA antibodies in serum may help manage problems related to food, especially food-sensitive enteropathies in children. IgA antibodies may also be an indicator of tolerance development.

Expected test values 

There are no recommended cut-off values for specific IgA antibodies in general as they are markers for antigen exposure and are not directly related to a disease. Results vary both within and between antigens. Geographical variations are also important, as are individual levels of exposure.

To determine if levels are increased, the reference level of specific IgA antibodies to a certain antigen must be measured in a number of samples from normal healthy individuals and, if possible, compared with the levels in a group of patients.

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 test 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 capsules. The hydrophilic, highly branched polymer provides an ideal microenvironment fo rallergens, binding them irreversibly while mainitaining their native structure.

The test is designed as a sandwich immunoassay. 

The antigen of interest, covalently coupled to the solid phase, reacts with the specific IgA antibodies in the patient sample.
After washing away non-specific IgA antibodies, enzyme labelled antibodies against IgA are added to form a complex.
After incubation, unbound enzyme-anti-IgA 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 IgA antibodies are present in the sample.