Passive hemagglutination reaction with dosed erythrocyte diagnosticum

The passive hemagglutination reaction (PHA) is one of the proven tools for serological diagnosis of infectious diseases. At the same time, its staging technique, which has remained virtually unchanged throughout the use of commercial erythrocyte diagnostic kits, does not always meet diagnostic requirements.
As is known, the main parameters of any serological reaction (united by the concept of "informativeness") are sensitivity, clarity, and specificity. In the case of R-PHA, the high level of the first two characteristics raises no doubts, but as for specificity, i.e. the ability to detect or exclude homologous antibodies in a higher titer than heterologous ones, it is impossible to unambiguously assess its degree. The specificity of PPGA is influenced by a number of reasons, and primarily by the properties of the erythrocyte diagnostic kits, which, thanks to industrial technology, can be considered unified and stable.