ABSTRACT
Objective Clinical significance of using ELISA to determine ?-amyloid(A?)_(1-42) antibody levels in the sera of patients with Alzheimer's disease(AD).Methods 96 wells PVC plate was coated with A?_(1-42)peptide.Serum of AD patient was competing with mouse A?_(1-42)monoclonal antibody in this assay.The second antibody was horseradish peroxidase(HRP)conjugated goat anti-mouse IgG.Serum A?_(1-42)antibody levels were determined by ELISA.Results The sensitivity of this assay was about 1 ng/ml.The recovery rate of this test was between 96.5% and 104.7%.The residual A?_(1-42)antibody levels in human serum or horse serum after A?_(1-42)antibody was removed by absorption were less than 1 ng/ml. Serum A?_(1-42)antibody levels in 37 AD patients[(5.1?1.9)ng/ml]were remarkably lower than those in normal people[(12.6?3.3)ng/ml,P