EliA Test Principle

The EliA test is a fluorescence enzyme immunoassay (FEIA) and is designed as a sandwich immunoassay.

A well is coated with an antigen which is specifically recognized by target antibodies, representing markers for a certain autoimmune disease. If these specific antibodies are present in the patient’s blood sample, they will bind to the antigen. In the subsequent reaction step, an enzyme-conjugated secondary antibody binds to the target antibody, bound to the antigen.

The enzyme transforms an added substrate into a fluorescent product. Through comparing the fluorescence signal with that of calibrators of known concentrations, the antibody concentration in the test sample can be determined.

The antigen of interest, coated to the solid phase, binds the specific  antibodies (e.g. of IgG class) in the patient sample.
After washing away unbound, non-specific antibodies, enzyme labelled antibodies against the target antibody (e.g. of IgG class) are added to form a complex.
After incubation, unbound enzyme labelled antibodies are 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 antibodies (e.g. of IgG class) are present in the sample.


As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.