Identification and quantitation of solubilized I blood group substance by wheat germ agglutinin using quantitative immunoelectrophoresis.

Wheat germ agglutinin (WGA) has been shown to react specifically with solubilized I blood group substance, purified from papain treated human erythrocyte membranes. WGA and I react to form an affinity precipitate in immunodiffusion gels, a reaction which can be blocked by the incorporation of N-acetyl glucosamine into the gel. The I material was a strong inhibitor of both anti-I cold hemagglutination and WGA hemagglutination reactions. Utilizing the techniques of crossed immunoelectrophoresis we have clearly established that WGA and anti-I IgM cold antibody are reacting with the same membrane macromolecule (I antigen). WGA was then used in a rocket affinoelectrophoretic assay system to quantitate I substance. The limits of detection in this system was 25 ng.