Affinity purification of monoclonal antibodies, using a bifunctional oligosaccharide hapten.

A bifunctional hapten was synthesized consisting of a blood group A active tetrasaccharide (A-tetra) and a blood group Le(a) active pentasaccharide lacto-N-fucopentaose II (LNF II), linked to each other with a phenylaminothiourea spacer connecting the reducing ends (A-tetra-LNF II). The hapten was demonstrated to retain both blood group A and Le(a) activity and could be easily bound to both monoclonal anti-A and anti-Le(a) affinity columns. Due to the strong temperature dependence of the two antibodies their binding to oligosaccharides, the bifunctional hapten could be utilized to achieve easy desorption in the final step of affinity purification of either monoclonal anti-Le(a) or anti-A. The system is postulated to have general applicability in affinity purification of any ligate that binds with an avidity too high to achieve non-denaturing desorption.