[Comparative analysis of the interaction of protein A from Staphylococcus aureus with native, reduced and aggregated IgG].

In a comparative study the affinity of rabbit and human IgG, native, reduced and aggregated by various methods, to protein A obtained from the cell wall of Staphylococcus aureus was determined. For this purpose the method of the passive hemagglutination inhibition test was developed. The affinity to protein A was found to grow considerably after specific or non-specific IgG aggregation and to decrease by 60% after local damage affecting the structure of the IgG molecule waist as a result of the dissolution of the disulfide bond between its heavy chains. The problem of similarity between such effector properties of IgG as its ability to activate the complement system and to combine with protein A is considered, as well as the problem of the pathogenetic role of immune complexes bound with protein A.