[Immunoglobulin receptors of group A Streptococcus].

It was shown in the gel precipitation tests that absorption of human and rabbit IgG or Fc-fragments obtained from human IgG group A streptococcal cultures results in inhibition of the reactions of these preparations with immunoglobulin sera. The reactions of F(ab')2-fragments with the corresponding sera are not inhibited during their absorption by the same cultures. The results obtained support the presence in a number of group A streptococcal cultures of immunoglobulin receptors (Ig-receptors) capable of reacting with Fc-parts of human and rabbit IgG. Pepsin treatment destroys Ig-receptors. These receptors could not be found by the method used in hydrochloric acid extracts prepared from streptococci containing the receptors. The method can be applied for determination of Ig-receptors in streptococcal cultures.