The immunoblot is basically a simplified version of the western blot used in protein analysis, in which the antigens are separated by electrophoresis and then deposited onto a nitrocellulose membrane.
For the immunoblot, individual purified antigens are deposited onto nitrocellulose strips. Autoantibodies from the sample can bind to these antigens and can then be made visible by a detection antibody, like in the ELISA method. Blot test systems are easy to use and allow for the simultaneous detection of multiple antibodies. They are thus particularly suited to screening applications and often also allow for a semi-quantitative analysis.