No title
After electrophoresis of an alkaline extract of type 15 group A streptococci, three main precipitation lines were obtained in diffusion experiments against commercial human polyclonal IgG (lines 1, 2 and 3). Nineteen of 23 sera (83%) from apparently healthy human individuals gave line 3, while 6 of them (26%) gave line 1. The sera giving line 1 did also give line 3. Line 2 was obtained with 2 sera