For in vitro diagnostic use. The RIDASCREEN® Total IgE test is an enzyme immunoassay (EIA) for the quantitative determination of IgE antibodies in human serum. This test should be used in association with the specific IgE test as an indicator for an atopic disease. However, it is also used to help interpret the results from a specific IgE test.
The purpose of the immune system is to defend the body against pathogenic bacteria, viruses and other microorganisms. The defence reaction serves to protect the organism on initial contact with the pathogens and immunise it on repeated contact. All allergic type I reactions are preceded by an initial contact phase without symptoms during which class E specific antibodies (IgE antibodies) are formed. On repeated contact with the allergens which trigger the reaction, these IgE antibodies react with the allergens and lead to the release of mediators (usually from mast cells or mastocytes) such as histamine, leucotrien and prostaglandine etc. which lead to the symptoms of the allergy.
When carrying out allergy diagnostics, the determination of increased total IgE indicates the presence of sensitisation or allergy. The highest IgE values are found with atopic dermatitis and may reach in excess of 20,000 IU/ml.
Increased total IgE values may also be caused by other diseases such as parasitoses and infectious diseases such as mycoplasma infections, whooping cough, HIV and malignant myelomas or even immune deficiency. Although very low total IgE values indicate that there is no allergy, it cannot be ruled out.
The test corresponds to an enzyme immunoassay (EIA) for the determination of antibodies. Anti-human IgE antibodies of non-human origin are bonded to the inner surfaces of the wells of a microwell plate. Human IgE antibodies present in the standards, controls and patient samples are bound by these antibodies. In the second step, an anti-human IgE antibody conjugated with alkaline phosphatase is added which attaches itself to the bound human IgE antibody. In the third step, a substrate is added which is dephosphorylated by the alkaline phosphatase. The resulting colour change from colourless to yellow is measured using a photometer at 405 nm and a reference wavelength of 620 nm. The intensity of the yellow colour is proportional to the quantity of IgE-antibodies in the serum. The results are expressed in IU/ml.
|Test format||Microtiter plate with 96 wells (12 strips with 8 removable wells each)|
|Incubation time||135 min|
|Cut-off||The standard curve for RIDASCREEN® Total IgE is calibrated against the international reference preparation “2nd WHO IRP 75/502 for human IgE”. |
Accurate information is not available because the overlap of the total IgE concentrations for allergic persons and non-allergic persons is very large and moreover standard values for the Total IgE values were a function of age. For this reason, the results obtained must always be interpreted in the light of the case history, the clinical picture and the results from the specific IgE test.