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.
ImmunoCAP® Specific IgE
ImunoCAP Specific IgE consists of complete allergens covering over 650 allergens, allergen components covering over 90 components and Phadiatop, a test designed to differentiate between atopic and non-atopic patients. Quantifying IgE antibodies with ImmunoCAP Specific IgE results in accurate evaluation of allergy patients.
Immunodiagnostics offers over 650 different allergens and 90 allergen components for sensitive and precise quantitative detection of allergen-specific IgE antibodies. IgE antibodies appear in human serum and plasma as a result of sensitization to a specific allergen. Measurement of circulating IgE antibodies provides an objective assessment of sensitization to an allergen. In general, low IgE antibody levels indicate a low probability of clinical disease, whereas high antibody levels to an allergen show good correlation with clinical disease.
The clinical value of quantitative testing
For the clinician
- IgE antibody development can be detected at an early stage, indicating sensitization, even before clinical symptoms have developed
- Helps explain the allergy march – the progression of allergic disease
- Helps explain the allergen load – the allergens that together contribute to allergic symptoms
- Provides clear directions for disease management
For the laboratory
- Truly quantitative measuring range from 0.1-100 kUA/L
- Intra-assay CV (%) comparable to routine clinical chemistry immunoassays
- Excellent consistency over time, and between countries, systems, labs and persons
Expected test values
ImmunoCAP Specific IgE detects IgE antibodies in the range 0 to 100 kUA /l, where A represents allergen-specific antibodies. The result is reported quantitatively. In clinical practice, 0.35 kUA /l has commonly been used as a cut-off. A large number of studies have been performed in which the clinical performance of ImmunoCAP Specific IgE tests in allergy diagnosis have been evaluated. Clinical performance is expressed as sensitivity, ranging from 84-95 %, and specificity, ranging from 85-94%. Sensitivity and specificity have been reported from multi-center studies including several hundred patients tested for a range of different allergens.
ImmunoCAP® Specific IgG
Quantifying IgG antibodies with ImmunoCAP Specific IgG results in improved patient evaluation. ImmunoCAP Specific IgG measures antigen-specific IgG antibodies in human serum and plasma. Specific IgG comprises antigen-specific antibodies of immunoglobulin class G. These antibodies are part of the natural defense system of the body and develop in response to contact with foreign substances.
The presence of IgG antibodies specific to a certain antigen is a marker of exposure to that antigen. Furthermore, the level of specific IgG in serum usually reflects the extent of exposure to that antigen. Measuring specific IgG antibodies may provide a range of valuable clinical information in several fields.
In allergic disease, specific IgG is used:
- In clinical studies with asthma, rhinitis, urticaria, eczema and gastrointestinal disorders
- As a marker for exposure in different lung diseases, e.g. allergic alveolitis, aspergilloma and aspergillosis
In monitoring immunotherapy, increased levels of specific IgG:
- Show a general (but not definitive) correlation with clinical outcome
- Show that the immune system is responding to the therapy
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.
Quantifying eosinophil cationic protein with ImmunoCAP ECP results in proper evaluation of asthma patients. ImmunoCAP ECP measures the level of Eosinophil Cationic Protein (ECP) in serum. Eosinophils are the cells chiefly responsible for producing the inflammation associated with asthma. When eosinophils in the airway are activated, they undergo degranulation causing airway epithelial damage. This can lead to chronic inflammatory disease of the airway.
Asthmatic patients with eosinophilic inflammation have elevated levels of ECP in serum and other body fluids such as bronchial alveolar fluid and (induced) sputum. A high level of serum ECP indicates inflammation, which is a risk factor for asthmatic patients.
Asthma therapy consists of suppressing chronic and persistent airway inflammation. Measuring ECP in a serum sample is an objective and direct way of estimating the severity of the airway inflammation and following the course of the disease.
ECP serum measurements can be used:
- For monitoring inflammation in asthma
- For guiding corticosteroid treatment in asthma
- To find non-compliant patients
Quantifying total tryptase levels with ImmunoCAP Tryptase results in evaluation of risk for severe reactions in venom allergic patients and is also used as one WHO diagnostic criterion for mastocytosis and a marker in haematological neoplasms. ImmunoCAP Tryptase measures the level of tryptase released by mast cells into serum. Mast cells play a key role in allergic reactions and increase in numbers under inflammatory conditions. When activated, they release a variety of mediators that lead to the signs and symptoms of allergic reactions, such as anaphylaxis. These mediators include tryptase and histamine. A transient increase in the level of tryptase in circulation after a patient suffers an anaphylactic reaction helps to identify and assess the extent of the reaction. A persistent elevated baseline level of tryptase is an indication of possible mastocytosis.
Assessing risk for anaphylactic reactions
Elevated baseline tryptase levels serve as a risk marker for certain patients to get severe anaphylactic reactions. Mature tryptase is stored in the granula of resting mast cells. It is released into the bloodstream during mast cell activation, either by IgE- or non-IgE mediated mechanisms. The transiently increased levels of mature tryptase serve as a clinical marker confirming severe reactions as anaphylaxis.
Clinical marker in severe insect venom reaction
In average the prevalence of systemic anaphylactic sting reactions is around 3 %. Up to 25 % of patients with severe venom reactions have an elevated baseline tryptase level. The importance of identifying these patients has been emphasized as they are predisposed for severe anaphylactic reactions. Increased levels may be, but need not necessarily be, due to an underlying mastocytosis.
Clinical marker in perioperative severe reactions
Elevated baseline tryptase levels indicate an increased mast cell burden and may serve as a risk factor for severe reactions during surgery. Sensitization (i.e. presence of specific IgE antibodies to substances which the patients are exposed to during surgery) is another risk factor. To confirm an anaphylactic reaction, the importance of measuring the transient increase of tryptase during the perioperative phase is well established.
Tryptase in mastocytosis and haematological neoplasms
Persistently elevated levels of tryptase proforms in blood reflect the increased abnormal mast cell burden in mastocytosis. These heterogeneous diseases are commonly associated with a mutation in the receptor for the stem cell factor (SCF), a cytokine enhancing survival and autonomous growth of the mast cells.
A diagnostic and prognostic significance of tryptase is also seen in haematological abnormalities and malignancies (neoplasms) irrespective if systemic mastocytosis is established or not.
Tryptase levels (or concentrations) also increase in nasal fluid in:
- Active allergic rhinitis
- Allergen challenge in patients with allergic rhinitis