[Evaluation of the indirect hemagglutination inhibition and radial immunodiffusion tests as methods of quantitative immunoglobulin determination].

In comparison with the radial immunodiffusion method, the sensitivity of the indirect hemagglutination test in determining the concentration of immunoglobulins G, M and A in various biological substrates (blood serum, saliva, cerebrospinal fluid, feces) was 35--100 greater. Under the action of proteolytic enzymes immunoglobulin fragmentation led to increase in the concentration of the Ig indices (according to the data of radial immunodiffusion) and produced no effect on the indices of the indirect hemagglutination test; The latter should be used to determine the immunoglobulins in the external secretions characterized by a low content of the given proteins and a marked probability of their proteolytic splitting. In assessing the results of the indirect hemagglutination test it should be remembered that it was less precise and less reproducible than the radial immunodiffusion method.