Immunochemical quantitation of antigens by single radial immunodiffusion

Abstract

When an unknown amount of antigen is allowed to diffuse radially from a well in a uniformly thin layer of antibody-containing agar for a sufficient time to allow all antigen to combine, the final area reached by the precipitate is directly proportional to the amount of antigen employed, and inversely proportional to the concentration of antibody. It is also shown that the temperature at which the plates are incubated has no perceptible influence upon the results. By standardizing the technical conditions of the experiment it is possible to use this principle for the immunochemical determination of antigens. In the experimental albumin-antialbumin system here described, the lower limit of the method was found to correspond to 0·0025 μg of antigen, and to an antigen concentrations of 1·25 μg per ml. The standard deviation of the antigen determinations was less than 2 per cent of the mean. © 1965.