Comparison of intravenous immunoglobulins for naturally occurring autoantibodies against amyloid-beta.

Intravenous immunoglobulins (IVIG) are currently used for therapeutic purposes in autoimmune disorders. Recently, we demonstrated the presence of naturally occurring antibodies against amyloid-beta (nAbs-Abeta) within the pool of IVIG. In this study, we compared different brands of IVIG for nAbs-Abeta and have found differences in the specificity of the nAbs-Abeta towards Abeta(1-40) and Abeta(1-42). We analyzed the influence of a pH-shift over the course of antibody storage using ELISA and investigated antibody dimerization at acidic and neutral pH as well as differences in the IgG subclass distributions among the IVIG using both HPLC and a nephelometric assay. Furthermore, we investigated the epitope region of purified nAbs-Abeta. The differences found in Abeta specificity are not directly proportionate to the binding nature of these antibodies when administered in vivo. This information, however, may serve as a guide when choosing the commercial source of IVIG for therapeutic applications in Alzheimer's disease.