Neuronal RNA in relation to alz-50 immunoreactivity in alzheimer's disease

Both defective nucleic acid metabolism/protein synthesis and the expression of an abnormal antigen recognized by the Alz‐50 antibody may be involved in the neuronal degeneration of Alzheimer's disease (AD). A multiparametric analysis involving Alz‐50 immunocytochemistry and azure B–RNA microdensitometry was developed to compare nucleic acid alterations in Alz‐50‐positive neurons to those in Alz‐50‐negative neurons of the brain of AD patients. Alz‐50‐immunoreactive neurons of the hippocampal endplate (Rose's H3‐H5 fields) and the subiculum exhibited significantly lower (by approximately 30%) total RNA contents than negative neurons of the corresponding region. The mean RNA content of Alz‐50‐positive neurons of the AD brain was also reduced in comparison to that of Alz‐50‐negative neurons of agematched, nondemented controls, whereas there were no significant differences between negative neurons of AD patients and controls. The hippocampus of nondemented controls was also found to contain Alz‐50‐immunoreactive neurons, although 20‐to 30‐fold fewer than the hippocampus of AD patients. In the controls, there was also a tendency toward reduced RNA levels in Alz‐50‐positive versus ‐negative neurons. These data suggest a relationship between Alz‐50 immunoreactivity and defective nucleic acid metabolism in the AD brain.