Autoimmunity laboratory

Nephelometry

Summary

Science

Clinical

Science

The principles of nephelometry, as with many immunological assays, rely on the reactions between antibodies (specific proteins of the immune system) and antigens (proteins that antibodies recognise as “foreign”). A single antibody is specific for one particular antigen and when these two come into contact they bind to each other strongly. These antigen/antibody structures bind to one another to form large aggregations and it is these “immune complexes” that are measured in nephelometry. The antibodies that are used to generate the immune complexes are created artificially by commercial companies and have a single specific affinity for the proteins that the laboratory wishes to measure. When the patient serum has been mixed with the commercial antibodies a light source is passed through the solution and sensitive detectors determine how much light is scattered by the presence of immune complexes in suspension. More immune complexes will form in solution with increasing amount of the protein in serum therefore the increase in light scatter is indicative of higher levels of protein. The exact amounts can be determined by comparing with the light scatter from solutions of known protein concentration.

• Background
• Clinical