Affiliations: [a] Department of Clinical Chemistry, Amsterdam, The Netherlands | [b] Department of Neurology, Amsterdam, The Netherlands | [c] Department of Psychiatry, Amsterdam, The Netherlands | [d] Department of Epidemiology & Biostatistics, Amsterdam, The Netherlands | [e] Alzheimer Center, VU University Medical Center, Amsterdam, The Netherlands
Correspondence:
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Correspondence to: S.D. Mulder, Department of Clinical Chemistry, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, the Netherlands. E-mail: sd.mulder@vumc.nl.
Note: [] Handling Associate Editor: Piotr Lewczuk
Abstract: Serum amyloid P (SAP) and C-reactive protein (CRP) are proteins involved in innate immunity. The expression of SAP and CRP is increased in Alzheimer's disease (AD) brain tissue, compared to healthy controls. Although both proteins are found in cerebrospinal fluid (CSF), their origin is unclear. We investigated if increased local production of SAP and CRP in AD brain results in higher levels in CSF with the use of index values. To study this, SAP, CRP, and albumin levels were determined in CSF and serum samples of 30 control (65 ± 11 years; 57% female) and 140 AD subjects (65 ± 9 years; 53% female). To correct for inter-individual differences in protein diffusion from blood to CSF, quotients (Q = CSF/serum) of SAP, CRP, and albumin and index values (Qprotein/Qalb) were calculated. The results showed no significant differences in SAP and CRP index values between control and AD subjects, although eight percent of individual AD patients showed evidence of intrathecal SAP or CRP production using the Reiber hyperbolic model. Interestingly, the SAP index value was much lower than expected, based on its molecular size. In conclusion, these data suggest that local production of SAP and CRP in the AD brain does not substantially contribute to the CSF levels.
Keywords: Alzheimer's disease, C-reactive protein, index value, serum amyloid p
