A monoclonal antibody assay technique for plasma and red cell acetylcholinesterase activity in Alzheimer's disease.

Acetylcholinesterases (AChE) in human plasma and red cells have been considered as possible markers for Alzheimer's disease. Findings however vary widely and no significant pattern has emerged. The present study has used a new technique for AChE assay based on a monoclonal antibody raised against red cell AChE. This allows AChE isoenzymes to be measured directly in the presence of non-specific cholinesterases without the need for inhibitors. AChE activity in plasma and red cells was assayed in Alzheimer's disease, multi-infarct dementia, Huntington's and alcoholic Korsakoff syndrome, and the results compared both between groups and with normal controls. No significant differences in either red cell or plasma enzyme activity were found by any of these comparisons. Our findings do not suggest that in the dementias peripheral AChE activity reflects altered central cholinergic function, nor that it is likely to prove a useful marker for Alzheimer's disease.