Accuracy of quantitative immunoglobulin assays by simple radial immunodiffusion

Investigations of the accuracy of quantitative immunoglublin assays (IgG, IgA, IgM) by simple radial immunodiffusion are reported. The normal values (n = 79) were in good agreement with those reported by other authors. The method is characterized by satisfactory precision and high sensitivity. Tests for accuracy resulted in almost complete agreement between expected and measured immunoglobulin concentrations. The specificity of the antibodies incorporated in the agar gel was determined by immunoelectrophoretic analyses. Additional tests on the influence of deep-freeze storage of the specimen sera on the immunoglobulin content showed that with increasing time of storage only the IgM concentrations decreased. Moreover, it was found that differences in filling volume, diffusion time and temperature of incubation considerably altered the diameter of the precipitate. The influence of these parameters on the quality of the analyses can be avoided by standardizing the test conditions.