Sambucus nigra lectin (EBL I+II, also known as SNA) is isolated from elderberry bark. This lectin has a molecular weight of 140 kDa and is composed of two ricin-related lectins. EBL I+II is a tetrameric glycoprotein with a recognition of the Neu5Ac(alpha2-6)Gal or GalNAc linkage in glycoconjugates.

EBL I+II is not blood group specific but it does agglutinate type A erythrocytes more strongly than either B or O cells. Trypsin treated erythrocytes react better than untreated cells. Neuraminidase treated erythrocytes react with this lectin due to the presence of terminal galactose resides.

EBL I is composed of an A-chain with enzymatic activity and a B-chain with carbohydrate-binding activity. EBL II consists only of carbohydrate-binding B-chains. EBL I+II induces caspase-dependent apoptosis at low concentrations (nM) order, leading to typical symptoms of cell death in sensitive cells. This effect seems independent from the catalytic activity of the A-chain, but depends on the carbohydrate binding B-chain.