Study of an anti-human transthyretin immunoadsorbent: Influence of coupling chemistry on binding capacity and ligand leakage

A variant of transthyretin (TTR Val30Met) has been identified as the main protein precursor of the amyloid fibrils deposited in familial amyloidotic polyneuropathy (FAP). Specific removal of TTR in an extracorporeal immunoadsorption procedure is currently under investigation as a possible treatment of FAP. Immunoadsorbents were constructed by immobilizing murine anti-TTR monoclonal antibody 88.6.BA9 onto agarose gel supports via several different coupling chemistries. The influence of coupling conditions such as pH and antibody density, and of perfusion variables, such as antigen concentration and applied flow-rate, on the TTR capture efficiency, was determined. Cyanogen bromide-, carbonyldiimidazole- and aldehyde-activated (ALD) supports conjugated with antibody at optimal pH, provided immunoadsorbents with comparable TTR binding capacities. Regarding stability, leakage was lowest for the ALD based immunoadsorbents, particularly at high pH.