[Streptococcal immunoglobulin Fc receptors as inductors of anti-immunoglobulins].
The activity of IgG Fc-receptor was studied in 71 strains of serological group A streptococci isolated from streptococcal infection patients and carriers. The group of practically healthy subjects and those with diseases of non-streptococcal origin were found to have almost identical streptococcal strain distribution for IgG FcR+ and IgG FcR- (42.4 and 57.6 per cent, respectively). In the strains isolated from streptococcal infection patients, IgG FcR+ strains made up 63.1 per cent. In rabbit immunization, the capacity of IgG FcR-positive strains that were isolated from patients to induce anti-immunoglobulin synthesis was revealed. The induced synthesis of anti-immunoglobulins was noted also in rabbit immunization with purified streptococcal IgG Fc-receptors of M15 streptococcus and rabbit IgG eluated with streptococcal Fc receptors. Possible mechanisms of anti-immunoglobulin synthesis in experimental immunization are discussed.