Quantitative removal of hepatitis B viral antigens from serum by a monoclonal IgM coupled to a biocompatible solid-phase support

We covalently linked to regenerated cellulose filters a high-affinity monoclonal IgM produced against epitopes that reside on hepatitis B viral surface antigen (HBsAg). Conditions were established whereby as much as 250 μg of anti-HBsAgIgM could be linked to 2-4 mg of regenerated cellulose acetate by using cyanogen bromide and trichloro-s-triazine coupling agents. The immunoreactivity of the monoclonal anti-HBsAg IgM was preserved, and quantitative binding studies with HBsAg suggests that more than one functional binding site on the IgM molecule was operative. The specificity of the monoclonal anti-HBsAg IgM was established by demonstrating that a nonspecific monoclonal IgM (against influenza hemagglutinin), when coupled to the filters under identical conditions, had no effect on removal of HBsAg from serum. Most importantly, the monoclonal anti-HBsAg IgM-coupled filters quantitatively removed low levels of HBsAg from serum; after the third pass through the filter, HBsAg was undetectable in the perfusate. Further, the stability of the covalent bond between the anti-HBsAg IgM and regenerated cellulose acetate was shown by the lack of detectable murine monoclonal anti-HBsAg IgM in filtered serum despite 50 passages through the filter. Thus, we have demonstrated that monoclonal IgM antibodies with pre-defined specificity, when coupled to a biocompatible solid-phase support, may serve as a high-affinity and specific immunoabsorbant for quantitative removal and recovery of viral antigens from human serum. By using this approach, specific removal and recovery of many other substances from serum or plasma would seem possible.