Immunoglobulin-sulfated polysaccharide interactions. Binding of agaropectin and heparin by human IgG proteins.

The interaction of immunoglobulins with certain acidic polysaccharides was demonstrated by the binding of the sulfated glycans agaropectin and heparin by certain human IgG proteins. Heparin-binding IgG proteins can distinguish between the molecular forms of heparin derived from porcine intestine, bovine lung, and rat skin. The major specificity of these proteins is for native and certain high molecular weight subunit components of rat skin heparin. The interactions with multi-chain and single chain rat skin heparin are stable under physiological conditions and involve the Fab and, more specifically, the Fv region of the IgG molecule. These reactions occur as a result of an electrostatic interaction between cationic sites on certain IgG proteins and anionic sulfate resides of agaropectin or heparin. The characteristics of heparin-IgG interaction resemble those of heparin with other plasma proteins, the interactions of which have biological significance.