Characterization of polyclonal autoantibodies specific for beta 2-microglobulin in multiple myeloma sera.

Among 185 sera from 62 patients with multiple myeloma, two serum samples with high beta 2-microglobulin (beta 2m) binding activity (S beta 2m-BA) were investigated. The S beta 2m-BA was shown to be distinct from the monoclonal component and to be represented by autoantibody of the IgG class. These antibodies were specific for beta 2m. They formed macromolecular complexes with beta 2m, indicating that at least two distinct epitopes of beta 2m can be recognized by these antibody molecules. The association-dissociation constants and antigen binding capacities of these autoantibodies were compared with that of monoclonal or polyclonal heterologous antibodies.