TEST DIRECTORY

Radio immunoassay (RIA)
A target antigen is labeled with radioactive isotope (RI) and bound to its specific antibodies which is then competitively reacted with an antigen in a specimen. After the antigen-antibody reaction, the bound labeled antigens (bound) are separated from the unbound ones (free), and the antigen concentration is determined based on the proportion of radioactivity.
　To separate the bound and free antigens (B/F separation), the following methods are used. Solid-phase method:Antibodies are linked to the solid phase. Double antibody method: Antigen-antibody complexes are bound to the second antibody and precipitated. Ammonium sulfate precipitation method: Antigen-antibody complexes are precipitated by ammonium sulfate. PEG method: Antigenantibody complexes are precipitated by a precipitation reagent.