Cognitive improvement in Alzheimer's disease (AD) patients treated with intravenous immunoglobulin (IvIg) has been attributed to its antibodies to amyloid beta (A beta) We compared the concentrations of specific antibodies to soluble A beta 1-42 conformations, namely A beta 1-42 monomer and A beta 1-42 soluble oligomers, between three IvIg preparations. Gamunex, Gammagard. and Flebogamma. To determine specific antibody Concentrations to these A beta 1-42 conformations. nonspecific binding of the IvIg preparations to the An reverse sequence, A beta 42-1. was subtracted These antibodies were measured in untreated IvIg preparations and also after they were treated to dissociate antibody-antigen complexes. because this procedure has been reported to increase the detectable levels of serum anti-A beta antibodies. Antibody levels to A beta 1-42 monomer were significantly higher in untreated Gamunex than in the other two IvIg preparations, and antibody-antigen dissociation increased the measured anti-A beta monomer concentrations in Gamunex and Gammagard Dissociated Gamunex and Gammagard had higher anti-A beta monomer levels than Flebogamma. Generally similar results were found for antibodies to soluble A beta 1-42 oligomers. with the exception that after antibody-antigen dissociation, only Gammagard had significantly higher antibody levels than Flebogamma. These differences in antibody concentrations to A beta 1-42 conformations (particularly to A beta 1-42 soluble oligomers, thought to be the most neurotoxic conformation of soluble A beta) and the increased availability of these antibodies after antibody-antigen complex dissociation have important implications for IvIg treatment of AD patients.
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