ImmunoCAP Specific IgG4

Quantifying IgG4 antibodies with ImmunoCAP Specific IgG4 results in proper evaluation of immunological response

 

ImmunoCAP Specific IgG4 measures antigen specific IgG4 antibodies in human serum and plasma. Measurement of specific IgG4 antibodies have been used in clinical studies of different allergic diseases such as asthma, rhinitis, urticaria, eczema and gastrointestinal disorders. In monitoring immunotherapy, increased levels of specific IgG4 antibodies are generally seen.

Expected test values

There is no common cut-off value for specific IgG4 antibodies, as these are markers for antigen exposure and are not directly related to the disease. Results vary both within and between antigens. To determine if levels are increased, the reference level of specific IgG4 antibodies to a certain antigen must be measured in a number of samples from normal healthy persons and, if possible, compared with the levels in a group of patients.

Specimen collection and preparation

  • Collect blood samples and prepare serum or plasma according to standard procedures
  • Keep specimens at room temperature (RT) for shipping purposes only
  • Store at 2 °C to 8 °C for 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 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 IgG4 antibodies in the patient sample.
After washing away non-specific IgG4 antibodies, enzyme labelled antibodies against IgG4 are added to form a complex.
After incubation, unbound enzyme-anti-IgG4 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 IgG4 antibodies are present in the sample.