Abstract
Many studies have been done on neurofibrillary tangles occurring in Alzheimer's disease using antibodies, but without agreement on the interpretation of the results. Immunochemical studies using antibodies to neurofilament and tau and the antibody, Alz50, were carried out to estaslish a common view. The results suggest that: 1) antibodies to neurofilament recognizing tangles react with the phosphorylated epitope of tau in paired helical filaments; 2) Alz50 reacts with abnormal tau, which has slower electrophoretic mobility than normal tau; and 3) a certain part of tau has the protease-resistant property in brains affected by the disease.