Abeta1-42 Detection in CSF of Alzheimer's disease is influenced by temperature: indication of reversible Abeta1-42 aggregation?
Amyloid-beta 1-42 (Abeta1-42), peptide detectable in cerebrospinal fluid (CSF), has been extensively studied as diagnostic marker for Alzheimer's disease; however, results are variable. We investigated whether Abeta1-42 detection in CSF may be affected by handling temperature after lumbar puncture. CSF was collected from patients affected by probable AD (n=27), other dementias (OD) (n=24), or other neurological disorders without cognitive impairment (OND) (n=23). After lumbar puncture, CSF samples were either maintained at 37 degrees C, or handled according to standard procedures and centrifuged at 4 degrees C for 10 min; thereafter, one aliquot was further stored at 4 degrees C and another at 37 degrees C, before freezing all samples 90 min later at -80 degrees C, pending analysis. Abeta1-42 and total tau were determined using a commercially available sandwich enzyme-linked immunosorbent assay ELISA. Reduced Abeta1-42 and increased total tau CSF levels were confirmed as characteristic hallmarks of the OD and AD groups, providing standard measurement in samples stored at 4 degrees C before freezing. However, avoiding cooling or reheating CSF from 4 to 37 degrees C before freezing strikingly increased the Abeta1-42 concentration detectable in the AD group (P<0.01), but not in control groups. The results indicate that a pool of Abeta1-42 cannot be detectable in the CSF of AD patients, because standard preanalytical cooling masks in some ways the epitope recognized by Abeta1-42 specific antibodies. Moreover, our study suggests that low temperature could induce Abeta1-42 conformational changes and multimeric aggregates in probable AD, but, more importantly, Abeta1-42 aggregation could be reversible.
Sancesario
Giulia M
GM
Clinical Biochemistry and Molecular Biology, Rome, Italy. sancesario@med.uniroma2.it
Esposito
Zaira
Z
Nuccetelli
Marzia
M
Bernardini
Sergio
S
Sorge
Roberto
R
Martorana
Alessandro
A
Federici
Giorgio
G
Bernardi
Giorgio
G
Sancesario
Giuseppe
G
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid* / Q000175:diagnosis*; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid* / Q000737:chemistry; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002624:Chemistry, Clinical / Q000379:methods / Q000592:standards; D015925:Cryopreservation; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000134:cerebrospinal fluid / Q000737:chemistry; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid* / Q000737:chemistry; D011487:Protein Conformation; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods* / Q000592:standards; D013129:Spinal Puncture; D013696:Temperature; D013997:Time Factors; D016875:tau Proteins / Q000134:cerebrospinal fluid
D016229:Amyloid beta-Peptides; D015415:Biomarkers; D000939:Epitopes; C054369:MAPT protein, human; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D016875:tau Proteins