title: Altered levels of acetylcholinesterase in Alzheimer plasma.
abstract: BACKGROUND
  Many studies have been conducted in an extensive effort to identify alterations in blood cholinesterase levels as a consequence of disease, including the analysis of acetylcholinesterase (AChE) in plasma. Conventional assays using selective cholinesterase inhibitors have not been particularly successful as excess amounts of butyrylcholinesterase (BuChE) pose a major problem.
  
  
  RESULTS
  Here we have estimated the levels of AChE activity in human plasma by first immunoprecipitating BuChE and measuring AChE activity in the immunodepleted plasma. Human plasma AChE activity levels were approximately 20 nmol/min/mL, about 160 times lower than BuChE. The majority of AChE species are the light G(1)+G(2) forms and not G(4) tetramers. The levels and pattern of the molecular forms are similar to that observed in individuals with silent BuChE. We have also compared plasma AChE with the enzyme pattern obtained from human liver, red blood cells, cerebrospinal fluid (CSF) and brain, by sedimentation analysis, Western blotting and lectin-binding analysis. Finally, a selective increase of AChE activity was detected in plasma from Alzheimer's disease (AD) patients compared to age and gender-matched controls. This increase correlates with an increase in the G(1)+G(2) forms, the subset of AChE species which are increased in Alzheimer's brain. Western blot analysis demonstrated that a 78 kDa immunoreactive AChE protein band was also increased in Alzheimer's plasma, attributed in part to AChE-T subunits common in brain and CSF.
  
  
  CONCLUSIONS
  Plasma AChE might have potential as an indicator of disease progress and prognosis in AD and warrants further investigation.
authors.affiliation: Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain.
authors.forename: María-Salud
authors.initials: MS
authors.lastname: García-Ayllón
authors.forename: Iolanda
authors.initials: I
authors.lastname: Riba-Llena
authors.forename: Carol
authors.initials: C
authors.lastname: Serra-Basante
authors.forename: Jordi
authors.initials: J
authors.lastname: Alom
authors.forename: Rathnam
authors.initials: R
authors.lastname: Boopathy
authors.forename: Javier
authors.initials: J
authors.lastname: Sáez-Valero
mesh_terms: D000110:Acetylcholinesterase / Q000097:blood*; D000368:Aged; D000544:Alzheimer Disease / Q000097:blood*; D015153:Blotting, Western; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male
chemical_list: D000110:Acetylcholinesterase