Specific removal of anti-A and anti-B antibodies using modified dialysis filters

Removal of anti-A and anti-B blood group antibodies from human blood has been shown to facilitate cross-matched kidney transplantation by preventing hyperacute rejection. Patients had anti-A and anti-B antibodies removed using plasmapheresis followed by immunoadsorption onto packed bead columns. The authors' group conducted pilot studies to assess the feasibility of selectively removing anti-A and anti-B antibodies directly from blood using modified dialysis filters. An anti-A and anti-B specific antigen was covalently attached to the lumenal surface of hollow fibers within selected commercial dialysis modules. The filters were able to reduce the anti-A and anti-B filters of 300 ml of blood to 2 or below. A low molecular weight fraction of the authors' antigen system was found to have no antibody binding capacity. The standard antigen was purified by removal of the low molecular weight fraction and a dialysis filter was modified using the purified antigen. This filter displayed a six-fold higher capacity than a dialysis filter modified with the same mass of standard antigen. Hence the authors expect that a dialysis filter modified with purified antigen at optimal antigen binding conditions may be able to significantly reduce the anti-A and anti-B filters of 2 L of blood. It is concluded that selective blood group antibody removal by antigen-modified dialysis filters is feasible and may be a simpler system than plasmapheresis followed by immunoadsorption.