Radial immunodiffusion to determine quantity of antigen (CAT#: STEM-MB-0183-WXH)

Circular wells are cut into the agar and antigen is introduced into the wells. Specific antigens to the impregnated antibodies diffuse through the agar in all directions from the well and react with the antibody present forming visible precipitate or a precipitin ring.

• Determine the quantity or concentration of an antigen in a sample.
• Estimation of the immunoglobulin classes in sera.
• Estimation of IgG, IgM antibodies in sera to influenza viruses.

1. An agar containing an appropriate antiserum (antibody) is poured in plates.
2. Carefully circular wells are cut and removed from the plates.
3. A single or series of standards containing known concentration of antigen are placed in separate wells, while control and “unknown” samples are placed in other remaining wells.
4. As the antigen diffuses radially, a ring of precipitate will form in the area of optimal antigen – antibody concentration.
5. The ring diameters are measured and noted.
6. A standard curve is prepared using the ring diameters of the standards versus their concentrations. This curve is then used to determine the concentration of the control and unknown samples.