Functional aspects and nature of the lipopolysaccharide-receptor of human erythrocytes.

Abstract

We have isolated for the first time from human erythrocytes a physicochemically homogeneous lipo-glycoprotein that is rich in neuraminic acid, has a molecular weight of 228,000, and prevents attachment to erythrocytes of unheated and heated, smooth and rough endotoxin of all gram-negative bacteria tested. It did not interact with other bacterial antigens and, therefore, is named lipopolysaccharide-receptor. The receptor activity is destroyed by proteases; lipid and neuraminic acid are not involved in the activity. We have established quantitatively with radioactive tracers that the receptor interacts with lipopolysaccharides and not with receptors on erythrocytes. The receptor blocks those lipopolysaccharide groupings that attach to erythrocytes. The action of the receptor is physical and reversible; it removes lipopolysaccharides fixed to red cells. While other compounds (namely, glycolipids, lipoproteins, and basic proteins) also inhibit attachment of lipopolysaccharide to cells, they are much less active, and those tested are unspecific.