Principle of the test
- For the determination of autoantibodies or antibodies against infectious agents, cells, tissue sections or purified, biochemically characterized substances are used as antigen substrates.
- If the sample is positive, specific antibodies in the diluted serum sample attach to the antigens coupled to a solid phase.
- In a second step, the attached antibodies are stained with fluorescein-labelled anti-human antibodies and visualized with the fluorescence microscope.
- Positive samples can be titrated in steps. The most suitable titration interval is provided by the dilution factor 3.162 (square root of 10). In this way, every second step represents in its denominator an integral power of 10 (1:10, 1:32, 1:100, 1 : 320, 1 : 1000, 1 : 3200, 1 : 10000 etc.).
Indirect immunofluorescence: a standardised technique for the determination of autoantibodies and antibodies against infectious agents
- High specificity: positive and negative samples produce a large difference in signal strength. Each bound antibody shows a typical fluorescence pattern depending on the location of the individual antigens.
- The entire antigen spectrum of the original substrate is available, thus allowing the detection of a large number of antibodies and achieving a higher detection rate.
- Immunofluorescence enables simultaneous detection of antibodies against several biochemically different antigens on one single biological substrate.
- The indirect immunofluorescence test is the analytical method of choice when it would be too difficult or too complicated to prepare the test antigens individually for enzyme immunoassays.