THE ADHESIVE SPECIFICITY OF THE SOLUBLE HUMAN LECTIN, IGE-BINDING PROTEIN, TOWARD LIPID-LINKED OLIGOSACCHARIDES - PRESENCE OF THE BLOOD GROUP-A, GROUP-B, GROUP-B-LIKE, AND GROUP-H MONOSACCHARIDES CONFERS A BINDING-ACTIVITY TO TETRASACCHARIDE (LACTO-N-TETRAOSE AND LACTO-N-NEOTETRAOSE) BACKBONES

The immunoglobulin E-binding protein, epsilon BP (also known as CBP35, Mac-2, L-34, and L-29), is a beta-galactoside-binding protein of approximately 30 kDa and a member of the animal lectin family termed S-type or S-Lac. Multiple biological activities have been attributed to this lectin such as mediation of IgE binding to the surface of Langerhans cells and activation of mast cells through binding to the high affinity IgE receptor. In order to better understand the cell-binding activity and the proposed role for epsilon BP as a biological response modifier, we have studied the specificity of binding of the radioiodinated epsilon BP to a series of lipid-linked, structurally defined oligosaccharide sequences of the lacto/neolacto family. The results show that the minimum lipid-linked oligosaccharides that can support epsilon BP binding are pentasaccharides of the lacto/neolacto series and that the lectin binds more strongly to oligosaccharides of this family that bear the blood group A, B, or B-like determinants than to those bearing blood group H. This preferential binding of epsilon BP is also manifest with whole cells, as erythrocytes of blood groups A and B are more strongly bound by epsilon BP than those of blood group O. Blood group Le(a) and Le(x) sequences are not bound by the lectin. The present results in the context of the earlier observations on the specificity and biological activity of epsilon BP raise the possibility that, in vivo, its degree of cell association and thresholds for activation of various cells of the immune system, and by inference allergic predispositions, may be influenced by blood group status and other polymorphic carbohydrate antigen systems based on lacto/neolacto backbones.