Absorption of human α2-macroglobulin with selected strains of streptococci

Abstract
A new interaction was observed between humanα 2-macroglobulin (α 2M) and selected strains of streptococci. The streptococci boundα 2M. After its elution from the bacteria,α 2M was demonstrated by immunoelectrophoresis against anti-humanα 2M. The binding ofα 2M to one streptococcal strain of serological group C and two of group G was confirmed by radial immunodiffusion. Treating the streptococci with trypsin reduced their reactivity withα 2M. On the other hand, prolonged treatment with 6M guanidine-HCl had no effect on theα 2M binding. Binding sites forα 2M were most likely protein structures on the streptococcal surface.