title: Monoclonal antibody Alz-50 reacts with bovine and human serum albumin.
abstract: Alz-50, a monoclonal antibody originally prepared using Alzheimer brain homogenates, reacts with PHF-tau and normal tau on immunoblots, and stains specific neuronal populations in sections from Alzheimer's disease brain. Although the Alz-50 epitope has been mapped to amino acids 2-10 present in all human tau isoforms, minimal Alz-50 immunoreactivity is present in tissue from control brain, suggesting Alz-50 binding may be dependent on tau conformational differences. The absence of conclusive results concerning Alz-50 binding presents the possibility of Alz-50 immunoreactivity with proteins other than tau. The present study demonstrates Alz-50 cross-reactivity with denatured bovine serum albumin (BSA) and human serum albumin (HSA). Using LA-N-5 neuroblastoma cells, BSA from serum-containing media was present in cell homogenates and was found to be Alz-50-reactive on immunoblots. In fact, Alz-50 (0.1 microgram/ml) recognized as little as 78 ng of BSA and 312 ng of HSA. Since Alz-50 does not recognize native BSA, blocking of immunoblots with 3% BSA did not alter Alz-50 reactivity with tau from LA-N-5 cells. On SDS-polyacrylamide gels, HSA (approximately 69 kDa) migrates very closely to the pattern of A68 (PHF-tau) from Alzheimer brain homogenates. Hence, the presence of BSA or other albumins in cell or brain homogenates may be an important concern when using the Alz-50 antibody.
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham 35294-0017.
authors.forename: P K
authors.initials: PK
authors.lastname: Davis
authors.forename: G V
authors.initials: GV
authors.lastname: Johnson
mesh_terms: D000544:Alzheimer Disease / Q000276:immunology*; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D016477:Artifacts; D003429:Cross Reactions; D016895:Culture Media, Serum-Free; D000939:Epitopes / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000276:immunology; D009447:Neuroblastoma / Q000276:immunology / Q000473:pathology; D011487:Protein Conformation; D012709:Serum Albumin / Q000276:immunology*; D012710:Serum Albumin, Bovine / Q000276:immunology*; D013045:Species Specificity; D014407:Tumor Cells, Cultured; D016875:tau Proteins / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D016895:Culture Media, Serum-Free; D000939:Epitopes; D009363:Neoplasm Proteins; D012709:Serum Albumin; D016875:tau Proteins; D012710:Serum Albumin, Bovine