ImmunoCAP Specific IgG4 measures antigen-specific IgG4 antibodies in human serum and plasma. Measurement of specific IgG4 antibodies has been used in clinical studies of various 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, because these are markers for antigen exposure and not directly related to the disease. Results vary both within and between antigens. To determine whether levels are increased, the reference level of specific IgG4 antibodies to a particular 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 in accordance with standard procedures
- Keep specimens at room temperature (RT) for shipping purposes only
- Store at 2-8 °C for up to one week, otherwise store at -20 °C
- Avoid repeated freezing and thawing
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 doctor after the evaluation of all clinical and laboratory findings.