Interrelation between the blood neutrophil damage test and the passive hemagglutination reaction in detecting antibodies

Statistical analysis of the results of examinations of vaccinees against plague has revealed that the values of the neutrophil damage index (NDI) and antibody titers as determined in the passive hemagglutination (PHA) test qualitatively (but not quantitatively) correlate. The statistical series for the PHA test and NDI belong to different variations, i. e. they describe different functions of antibodies with respect to the same antigen. Besides, the determination of NDI permits the detection of antibodies in 95% of cases with probability equal to 0.06, while the PHA test determines antibodies in 67% of the vaccinees with probability equal to 0.30. The determination of NDI, used as an alternative qualitative method for antibody detection, is particularly effective in the evaluation of faintly immunogenic antigens, as well as at the early and late periods of immune state.