Abstract
Eight freshly isolated type M4 strains of group A streptococci were found to bind between 60 and 80% of 2.5 μg radiolabelled IgA myeloma protein in a standard test system, while a reference type 4 strain bound only 20%. Commercial human IgG or IgGl myeloma protein did not inhibit the binding of IgA by the reference type 4 strain or one of the freshly isolated type 4 strains, whereas inhibition was obtained by purified polyclonal IgA and IgA I myeloma protein. Fc fragments of purified IgA I myeloma protein, obtained by digestion with gonococcal protease, inhibited binding of radiolabelled IgA I, while the Fab fragments had no inhibitory effect.

This publication has 14 references indexed in Scilit: