A radiobinding assay is a method of detecting and quantifying

antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

targeted toward a specific

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

. As such, it can be seen as the inverse of

radioimmunoassay A radioimmunoassay (RIA) is an immunoassay that uses radiolabeled molecules in a stepwise formation of immune complexes. A RIA is a very sensitive in vitro assay technique used to measure concentrations of substances, usually measuring antigen conc ...

, which quantifies an antigen by use of corresponding antibodies. __TOC__

Technique

The corresponding antigen is

radiolabel A radioactive tracer, radiotracer, or radioactive label is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tr ...

ed and mixed with the fluid that may contain the antibody, such as

blood serum Serum () is the fluid and solute component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum includes all proteins not u ...

from a person. Presence of antibodies causes precipitation of antibody-antigen complexes that can be collected by

centrifugation Centrifugation is a mechanical process which involves the use of the centrifugal force to separate particles from a solution according to their size, shape, density, medium viscosity and rotor speed. The denser components of the mixture migrate ...

into pellets. The amount of antibody is proportional to the radioactivity of the pellet, as determined by

gamma counting A gamma counter is an instrument to measure gamma radiation emitted by a radionuclide. Unlike survey meters, gamma counters are designed to measure small samples of radioactive material, typically with automated measurement and movement of mult ...

.Anti-dsDNA [I-125] Radiobinding Assay Kit
At PerkinElmer Life Sciences, Inc. Retrieved Jan 2011

Uses

It is used to detect most

autoantibodies An autoantibody is an antibody (a type of protein) produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases (notably lupus erythematosus) are associated with such antibodies. Pr ...

seen in

latent autoimmune diabetes Slowly evolving immune-mediated diabetes, or latent autoimmune diabetes in adults (LADA), is a form of diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglyce ...

References

Immunologic tests {{immunology-stub