Fibronectin-mediated binding of group A streptococci to human polymorphonuclear leukocytes

Human plasma was shown to promote the attachment of an avirulent strain of Streptococcus pyogenes to human polymorphonuclear leukocytes. Removal of the fibronectin by absorption of the plasma with agarose-immobilized gelatin abolished the attachment-promoting activity. The activity of the absorbed plasma was restored with purified human serum fibronectin. The fibronectin was found to promote the attachment of three M protein-negative, but not of three M protein-positive, strains of streptococci. Radiolabeled fibronectin was shown to bind in various degrees to all strains of S. pyogenes tested. Thus, in the absence of streptococci surface M protein, fibronectin promotes the association of group A streptococci with human polymorphonuclear leukocytes.