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EliA - Phadia, now Thermo Fisher Scientific

EliA - Phadia, now Thermo Fisher Scientific

The EliA test is a fluorescence enzyme immunoassay (FEIA) and is designed as a sandwich immunoassay. A well is coated with an antigen that is specifically recognized by target antibodies, representing markers for a particular autoimmune disease.


If these specific antibodies are present in the patients 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. Comparing the fluorescence signal with that of calibrators of known concentrations enables the antibody concentration in the test sample to 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 unbound, non-specific antibodies have been washed away, 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 the reaction has been stopped, 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.