Comparison of ELISA measurements of anti-Aβ concentrations and percentages of specific binding to Aβ between unfractionated intravenous immunoglobulin products and their purified anti-Aβ antibodies.
Intravenous immunoglobulin (IVIG) products are being investigated as possible therapeutic agents for mild cognitive impairment and Alzheimer's disease (AD). Anti-Aβ antibodies have been measured by ELISA in unfractionated IVIG products and in affinity-purified antibodies from these products, but it is unclear if similar results are obtained with these two approaches. Measurements of anti-Aβ antibodies in unfractionated IVIG may be confounded by the presence of polyvalent antibodies which can bind to multiple antigens, including those on ELISA plates; whether this is an issue when measuring anti-Aβ antibodies in purified antibody eluates from IVIG is also unknown. The objective of this study was to clarify these issues. The concentrations of specific antibodies to Aβ1-42 monomer and the percentages of specific binding to it were compared via ELISA between three unfractionated IVIG products (Gamunex [Talecris], Gammagard [Baxter], and Flebogamma [Grifols]) and their affinity-purified anti-Aβ antibodies. The concentrations of anti-Aβ antibodies in unfractionated IVIG products were higher than in their respective purified anti-Aβ eluates, and the rank order of the IVIG products with respect to their anti-Aβ concentrations differed between the two types of samples. The percentages of specific binding to Aβ were lower for unfractionated IVIG than for purified anti-Aβ eluates. These findings indicate that ELISA measurements of specific anti-Aβ antibodies and percentages of specific binding to Aβ produce different results depending upon whether these measurements are made in unfractionated IVIG products or their purified anti-Aβ antibodies. Polyvalent binding occurs even with purified anti-Aβ antibodies eluated from IVIG products, but it is less extensive than with unfractionated IVIG.
Department of Neurology Research, Beaumont Health System, Royal Oak, MI, United States. Electronic address: Andrea.Klaver@beaumont.edu.
Andrea C
AC
Klaver
Mary P
MP
Coffey
Lynnae M
LM
Smith
David A
DA
Loeffler
D000544:Alzheimer Disease / Q000276:immunology / Q000628:therapy*; D016229:Amyloid beta-Peptides / Q000276:immunology; D000915:Antibody Affinity; D001323:Autoantibodies / Q000378:metabolism*; D005591:Chemical Fractionation; D045424:Complex Mixtures / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000378:metabolism* / Q000627:therapeutic use; D007163:Immunosorbent Techniques; D007167:Immunotherapy / Q000379:methods*; D010446:Peptide Fragments / Q000276:immunology; D011485:Protein Binding
D016229:Amyloid beta-Peptides; D001323:Autoantibodies; D045424:Complex Mixtures; D016756:Immunoglobulins, Intravenous; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)
Abeta; Affinity chromatography; Antibody; Binding specificity; ELISA; Intravenous immunoglobulin