Effect of Different Aß Aggregates as Antigen on the Measure of Naturally Occurring Autoantibodies against Amyloid-ß40/42 in IVIG.

BACKGROUND: The specific Intravenous Immunoglobulin (IVIG) for Alzheimer's Disease (AD) is developing, which contains a high level of naturally occurring autoantibodies against amyloid-ß (nAbs-Aß), and the measure of nAbs-Aß content is greatly essential. Though Enzyme-Linked Immunosorbent Assay (ELISA) has been widely used in detecting the nAbs-Aß content, the impact of Aß aggregates species chosen as antigen in ELISA on this measure has not been evaluated. OBJECTIVE: To clarify the influence of different Aß40/42 aggregates as antigen during ELISA on the content of nAbs-Aß40/42 measured in IVIG. METHOD: Preparation of various Aß40/42 aggregates was performed by different aggregation solutions and various lengths of time, and analyzed by western blot. Different Aß40/42 aggregates as antigen were adopted to measure the nAbs-Aß40/42 content in IVIG by ELISA, and the control was carried out to reduce interference of nonspecific binding. The Bonferroni and Dunnett's T3 were used for statistical analysis. RESULTS: The duration for the formation of Aß40/42 aggregates had more effect on detecting nAbs-Aß40/42 content in IVIG than the aggregation solution. Higher content of nAbs-Aß40/42 in the same IVIG was displayed when measured with Aß40/42 aggregates at day 3, instead of at day 0.5 and day 7.0. The nAbs- Aß40/42 contents in the same IVIG measured with Aß40/42 aggregates prepared in different solutions were obviously different, but there was no significant regularity among them. CONCLUSION: The nAbs-Aß40/42 content in the same IVIG is significantly different when measured with Aß40/42 aggregated under different conditions. The nAbs-Aß40/42 content in IVIG by antigen-dependent measures, like ELISA, is uncertain.

Concentrations of antibodies against ß-amyloid 40/42 monomer and oligomers in Chinese intravenous immunoglobulins.

Intravenous immunoglobulin (IVIg) preparations are being investigated as a potential agent for treatment or prevention of Alzheimer's disease (AD). Antibodies towards soluble ß-amyloid (Aß) contained in IVIg were considered to be the major component contributing to the beneficial effect of the preparations in pilot studies. This study compared the antibody concentrations against Aß in Octagam® IVIg (Octapharma) and 9 IVIg preparations from different Chinese manufacturers by ELISA, using Aß40 monomer, Aß40 soluble oligomers, Aß42 monomer and Aß42 soluble oligomers as the antigens. The results showed that each preparation contained different antibody levels against the four Aß forms. The median values of the four antibody concentrations in Chinese IVIg preparations were 16.53, 8.47, 24.36 and 33.25µg/mL, which were remarkably higher than that in Octagam® IVIg (1.66, 2.07, 4.61 and 4.64µg/mL). Moreover, the anti-Aß42 oligomer antibody levels in almost all IVIg preparations were higher than the anti-Aß42 monomer antibody, and the concentrations of anti-Aß42 antibodies in most of the IVIg preparations were significantly higher than that of anti-Aß40 antibodies. These findings will contribute to an increased understanding of the uniqueness of Chinese IVIg preparations, and could provide support for a trial of a Chinese IVIg product in AD patients.