[The assessment of the parallelism in the results of measuring an analyzable substance and the calibrator in immunological assays]. 
The method for checking the results of measurements of the analyzed substance and the calibrator for parallelism the immunological testing kit ABICAP-test-DIPHTHERIA, produced by ABION (Germany), is described.  The international standard sample of diphtheria antitoxin human serum was used as calibrator, and human serum No.  18, obtained from the Biomed Group (Russia), was used as the substance to be analyzed.  The described method made it possible to detect the parallelism of "dose-response" curves with the relative error not exceeding 20%.  Such accuracy proved to be sufficient for practical purposes and was in agreement with the amplitude of oscillations in measured optical densities.  The shift of graphs along the abscissa made it possible to estimate the concentration of the serum as exceeding the concentration of the standard sample 2.3 times.  The use of analytical approximation for the standard seems to be an important feature in the described method.