Direct and Indirect ELISA
In principle, there are two possible approaches to the implementation of an ELISA test: for direct ELISA, antibodies directed against the protein being sought are bound to the plate. The protein being detected binds to these antibodies and can be detected in a second step by a second enzyme-marked antibody.
The detection of (auto)antibodies is based on indirect ELISA. For this type of test, the microtitre plate is first coated with the autoantigen to which these antibodies bind.