Euonymus europaeus lectin or agglutinin (EEL/EEA) is isolated from the spindle tree. It is a glycoprotein with a molecular weight of 140 kDa and is composed with most of the subunits that appear to consist of two chains linked by disulfide bonds. EEL consists of six closely related lectins (isoforms) with isoelectric points between pH 4.3 and pH 4.7.

EEL is identified for its erythrocyte agglutinating properties and specificity for blood groups B and H. Studies have shown a stronger binding of the H trisaccharide over the B trisaccharide, but with general pattern of the lectin interacting with both B and H blood groups and beta-mannose-terminated saccharides. EEL has a preferential recognition of terminal beta-fucose residues in H and B blood group-related carbohydrates. This lectin binds to endothelial cells from human and non-human sources, and recognizes carbohydrate structures on the surface of stimulated murine peritoneal lymphoid cells.