Reduced levels of amyloid beta-peptide antibody in Alzheimer disease

Objective: To investigate whether it was possible to detect the presence an d different levels of naturally occurring anti-beta -amyloid (A beta) antib odies in the CSF of patients with AD and age-matched controls by employing a sensitive ELISA. Background: Immunization with preaggregated amyloid beta -peptide (A beta (1-42)) and administration of antibodies against A beta i nto amyloid precursor protein APP(V717F)-transgenic mice (an animal model o f AD) have recently been reported to dramatically reduce amyloid plaque dep osition, neuritic dystrophy, and astrogliosis, most likely by enhancing A b eta clearance from brain. Methods: A sensitive ELISA was performed to detec t levels of naturally occurring anti-A beta antibodies in the CSF of patien ts with AD and age-matched controls. Additionally, an immunoprecipitation a ssay was performed to confirm that naturally occurring anti-A beta antibodi es also exist in the human blood. Result: Naturally occurring antibodies di rected against A beta were found in the CSF and plasma of patients with AD and healthy control subjects. Moreover, CSF anti-A beta antibody titers are significantly lower in patients with AD compared with healthy control subj ects. Conclusion: Naturally occurring antibodies directed against A beta ex ist in human CSF and plasma. The CSF anti-A beta antibody titers may be hel pful in better understanding the effects of future immunologic therapies fo r AD.