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Assessment of Preanalytical Cerebrospinal Fluid Handling and Storage Factors on Measurement of Aβ1-42, Aβ1-40, and pTau181 Using an Automated Chemiluminescent Platform.

Author(s): Ho S, Darrow J, De Simone F, Calabro A, Gannon S, Esquivel R, Thakker P, Khingelova K, Rao A, Zhang Y, Moghekar A

Publication: J Appl Lab Med, 2024, Vol. , Page

PubMed ID: 38712812 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study evaluated the effects associated with cerebrospinal fluid (CSF) collection tube type, storage at different temperatures (4°C for 1 week, -80°C for 1 month), and specimen contact with the cap of the collection tube on the concentrations of β-amyloid1-42 (Aβ1-42), β-amyloid1-40 (Aβ1-40), phosphorylated tau (pTau181). CSF was collected by lumbar puncture using a 22-gauge Quincke needle from 28 patients (2 with AD, 8 with NAD, and 18 with NPH) into four tubes of each of the following types per patient: 1.5 mL Sarstedt polypropylene tube, 10 mL Sarstedt polypropylene tube, 2.5 mL Sarstedt polypropylene tube. CSF specimens were transported at room temperature, centrifuged at 2000 x g for 10 min at 5°C within 2 h of collection, and immediately analyzed to establish baseline values for β-amyloid1-42 (Aβ1-42), β-amyloid1-40 (Aβ1-40), and phosphorylated tau (pTau181) concentrations of the automated LUMIPULSE G1200 chemiluminescent enzyme immunoassay. For each patient, two CSF tubes were stored at 4°C for 1 week (one tube upright, one tube inverted), and two CSF tubes were stored at -80°C for 1 month (one tube upright, one tube inverted).  All CSF tubes were thawed in an upright position and vortexed for 10 s before analysis.

   Summary of Findings:

   CSF storage at 4°C for 1 week or at -80°C for 1 month did not significantly affect concentrations of Aβ1-42, Aβ1-40, or pTau181 or the ratio of Aβ1-42/1-40 or pTau181/ Aβ1-42 relative to baseline data collected from fresh specimens, although some collection tube-specific effects were observed.  Contact between the CSF sample and the cap of the collection tube resulted in a significant decrease in Aβ1-42 concentration when the 2.5 mL Sarstedt polypropylene tube was stored inverted (P<0.05). Variable concentrations (±5%) in Aβ1-40, Aβ1-42, and pTau181/ Aβ1-42 were observed among tube orientations and storage timepoints for the 2.5 mL polypropylene tube, and significant differences in Aβ1-42 (P=0.003), Aβ1-40 (P=0.011), and pTau181 (P=0.048) occurred when levels from the 2.5 mL and 1.5 mL polypropylene tubes were directly compared. The concentration of pTau181 also displayed a significant decrease with storage when the 10 mL Sarstedt polypropylene tube was stored upright (P<0.05). 

   Biospecimens

   • Bodily Fluid - Cerebrospinal Fluid

   Preservative Types

   • Frozen

   Diagnoses:

   • Alzheimer's Disease
   • Other diagnoses
   • Hydrocephalus

   Platform:

   Analyte	Technology Platform
   Peptide	Chemiluminescence immunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage temperature	4°C for 1 week -80°C for 1 month
   Biospecimen Acquisition	Type of collection container/solution	1.5 mL Sarstedt polypropylene tube 2.5 mL Sarstedt polypropylene tube 10 mL Sarstedt polypropylene tube
   Storage	Storage conditions	Tube upright Tube inverted

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2. Study Purpose

   This study evaluated the effects associated with cerebrospinal fluid (CSF) collection tube volume and different methods of mixing the CSF sample post-thaw on the concentrations of β-amyloid1-42 (Aβ1-42), β-amyloid1-40 (Aβ1-40), phosphorylated tau (pTau181). CSF was collected by lumbar puncture using a 22 -gauge Quincke needle from 10 patients (2 that were cognitively normal, 1 with AD, 2 with NAD, and 5 with NPH) into four tubes of each of the following per patient: 1.5 mL and 10 mL Sarstedt polypropylene tube.  CSF specimens were transported at room temperature, centrifuged at 2000 x g for 10 min at 5°C within 2 h of collection, and immediately analyzed to establish baseline values for Aβ1-42, Aβ1-40, and pTau181 concentrations of the automated LUMIPULSE G1200 chemiluminescent enzyme immunoassay. The remaining samples were stored at -80°C for ≥8 h, thawed at room temperature for ≥1 h, and analyzed without being mixed or after tube inversion (10 times), vortexing for 10 s, or placement on a horizontal roller for 20 min. 

   Summary of Findings:

   While no significant differences in the concentration of Aβ1-42, Aβ1-40, or pTau181 were present among CSF specimens that were mixed by inversion, vortexing, or horizontal roller post-thaw and before analysis, significant differences were observed in pTau181 (P=0.002) and the ratio of pTau181/ Aβ1-42 (P<0.001) among unmixed CSF samples collected in the two different tube volumes.

   Biospecimens

   • Bodily Fluid - Cerebrospinal Fluid

   Preservative Types

   • Frozen

   Diagnoses:

   • Alzheimer's Disease
   • Other diagnoses
   • Hydrocephalus

   Platform:

   Analyte	Technology Platform
   Peptide	Chemiluminescence immunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Type of collection container/solution	1.5 mL Sarstedt polypropylene tube 10 mL Sarstedt polypropylene tube
   Biospecimen Aliquots and Components	Biospecimen mixing	Unmixed Inversion Vortex Horizontal roller

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3. Study Purpose

   This study evaluated the effects associated with freeze-thaw cycling CSF specimens on the concentrations of β-amyloid1-42 (Aβ1-42), β-amyloid1-40 (Aβ1-40), phosphorylated tau (pTau181). CSF (8 mLs per patient) was collected by lumbar puncture using a 22-gauge Quincke needle from 15 patients (1 that was cognitively normal, 2 with AD, 6 with NAD, and 6 with NPH) into a 10 mL Sarstedt polypropylene tube. CSF specimens were transported at room temperature, centrifuged at 2000 x g for 10 min at 5°C within 2 h of collection, and immediately analyzed to establish baseline values for Aβ1-42, Aβ1-40, and pTau181 concentrations of the automated LUMIPULSE G1200 chemiluminescent enzyme immunoassay. The specimen collected from each patient was divided into 1.2 mL aliquots among four 1.5 mL Sarstedt polypropylene tubes that were stored at -80°C for ≥45 min. CSF aliquots were subjected to 1, 2, 3, or 4 freeze-thaw cycling events where the aliquot was thawed at room temperature for 30 min, vortexed for 10 s, and analyzed.

   Summary of Findings:

   The concentration of Aβ1-42 in CSF exhibited a significant decrease relative to the baseline value (fresh CSF specimen) following 2 (P=0.029), 3 (P=0.025), and 4 (P=0.010) freeze-thaw events; CSF concentrations of Aβ1-40, pTau181, and the ratio of Aβ1-42/1-40 were not significantly affected by up to 4 freeze-thaw cycles.

   Biospecimens

   • Bodily Fluid - Cerebrospinal Fluid

   Preservative Types

   • Frozen

   Diagnoses:

   • Alzheimer's Disease
   • Other diagnoses
   • Hydrocephalus

   Platform:

   Analyte	Technology Platform
   Peptide	Chemiluminescence immunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Freeze/thaw cycling	0 cycles 1 cycle 2 cycles 3 cycles 4 cycles

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