Quantification of amyloid-beta 40 in cerebrospinal fluid.
BACKGROUND
Truncated forms and full-length forms of the amyloid-beta 40 (Abeta40) are key molecules in the pathogenesis of dementia, and are detectable in CSF. Reliable methods to detect these biomarkers in CSF are of great importance for understanding the disease mechanisms and for diagnostic purposes.


METHODS
VU-alpha-Abeta40, a monoclonal antibody (mAb) specifically detecting Abeta40, was generated and characterized by solid and fluid phase ELISA, surface plasmon resonance spectroscopy (SPRS), immunoprecipitation (IP), immunohistochemical and Western blot (WB) analysis. In addition, an ELISA with VU-alpha-Abeta40 as catching and 6E10 as detecting mAbs was set up and validated. This ELISA was used to measure Abeta40 in CSF of controls (N=27), patients with Alzheimer's disease (AD; N=20), frontotemporal lobe dementia (FTLD; N=14), noninflammatory (N=15) and inflammatory (N=15) neurological conditions.


RESULTS
VU-alpha-Abeta40 specifically recognizes Abeta40 with high affinity (K(A)=1.3x10(9) M(-1)) and detects Abeta40 in AD brain specimens. The developed sandwich ELISA has a detection limit of 0.21 ng/mL, a mean recovery of 90%, and an intra- and inter-assay CV of 1.4% and 7.3%. FTLD patients had a lower mean level of Abeta40 (8.8 (1.9) ng/mL) than controls (12.0 (1.7) ng/mL); p<0.01).


CONCLUSIONS
VU-alpha-Abeta40 was successfully implemented in an ELISA which enables us to measure Abeta40 accurately in human CSF. Clinical validation revealed lower levels of Abeta40 in FTLD patients. This finding opens new possibilities for early and differential diagnosis of dementia.
Verwey
Nicolaas A
NA
Department of Neurology, VU University Medical Center, Alzheimer Center Amsterdam, P.O. Box 7057, 1007 MB Amsterdam, the Netherlands. n.verwey@vumc.nl
Veerhuis
Robert
R
Twaalfhoven
Harry A M
HA
Wouters
Dorine
D
Hoozemans
Jeroen J M
JJ
Bollen
Yves J M
YJ
Killestein
Joep
J
Bibl
Mirko
M
Wiltfang
Jens
J
Hack
C Erik
CE
Scheltens
Philip
P
Blankenstein
Marinus A
MA
D000368:Aged; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid* / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology; D015415:Biomarkers / Q000134:cerebrospinal fluid; D003704:Dementia / Q000134:cerebrospinal fluid* / Q000175:diagnosis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid* / Q000276:immunology
D016229:Amyloid beta-Peptides; D000911:Antibodies, Monoclonal; D015415:Biomarkers; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40)