Browsing by Subject "Immunoassay"

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    Comparing the Clinical Utility and Diagnostic Performance of CSF P-Tau181, P-Tau217, and P-Tau231 Assays
    (Wolters Kluwer, 2021) Leuzy, Antoine; Janelidze, Shorena; Mattsson-Carlgren, Niklas; Palmqvist, Sebastian; Jacobs, Dirk; Cicognola, Claudia; Stomrud, Erik; Vanmechelen, Eugeen; Dage, Jeffrey L.; Hansson, Oskar; Neurology, School of Medicine
    Background and objectives: Phosphorylated tau (p-tau) in CSF is considered an important biomarker in Alzheimer disease (AD) and has been incorporated in recent diagnostic criteria. Several variants exist, including p-tau at threonines 181 (p-tau181), 217 (p-tau217), and 231 (p-tau231). However, no studies have compared their diagnostic performance or association to β-amyloid (Aβ) and tau-PET. Understanding which p-tau variant to use remains an important yet answered question. We aimed to compare the diagnostic accuracy of p-tau181, p-tau217, and p-tau231 in CSF for AD and their association with Aβ and tau-PET. Methods: A total of 629 participants in the Swedish BioFINDER-2 study were included (cognitively unimpaired, n = 334; Aβ-positive mild cognitive impairment, n = 84; AD dementia, n = 119; and non-AD disorders, n = 92). In addition to p-tau181 and p-tau217 measured using assays with the same detector antibodies from Eli Lilly (p-tau181Lilly, p-tau217Lilly) and p-tau231, we also included p-tau181 measurements from 2 commonly used assays (Innotest and Elecsys). Results: Although all p-tau variants increased across the AD continuum, p-tau217Lilly showed the greatest dynamic range (13-fold increase vs 1.9-5.4-fold increase for other p-tau variants for AD dementia vs non-AD). P-Tau217Lilly showed stronger correlations with Aβ- and tau-PET (p < 0.0001). P-Tau217Lilly exhibited higher accuracy than other p-tau variants for separating AD dementia from non-AD (area under the curve [AUC], 0.98 vs 0.88 [p < 0.0001] - 0.96 [p < 0.05]) and for identifying Aβ-PET (AUC, 0.86 vs 0.74 [p < 0.0001] and 0.83 [p < 0.001]) and tau-PET positivity (AUC, 0.94 vs 0.80-0.92, p < 0.0001). Finally, p-Tau181Lilly generally performed better than the other p-tau181 assays (e.g., AD dementia vs non-AD, AUC, 0.96 vs 0.88 [p-tau181Innotest] and 0.89 [p-tau181Elecsys]; p < 0.0001). Discussion: CSF p-tau217Lilly seems to be more useful than other included p-tau assays in the workup of AD. Varied results across p-tau181 assays highlights the importance of anti-tau antibodies for biomarker performance. Classification of evidence: This study provides Class II evidence that p-tau217 provides higher diagnostic accuracy for diagnosis of AD dementia than p-tau181 or p-tau231.
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    Preprogrammed, Parallel On-Chip Immunoassay Using System-Level Capillarity Control
    (ACS, 2013) Kim, Sung-Jin; Paczesny, Sophie; Takayama, Shuichi; Kurabayashi, Katsuo; Pediatrics, School of Medicine
    Fully manual use of conventional multiwell plates makes enzyme-linked immunosorbent assay (ELISA)-based immunoassays highly time-consuming and labor-intensive. Here, we present a capillarity-driven on-chip immunoassay that greatly saves time and labor with an inexpensive setup. Our immunoassay process starts with pipetting multiple solutions into multiwells constructed on a microfluidic device chip. Subsequently, capillarity spontaneously transports multiple sample solutions and common reagent solutions into assigned detection channels on the chip in a purely passive and preprogrammed manner. Our device implements capillarity-driven immunoassays involving four sample and six reagent solutions within 30 min by orchestrating the functions of on-chip passive components. Notably, our immunoassay technique reduces the total number of pipetting processes by ~5 times, as compared to assays on multiwell plates (48 vs 10). This assay technique allows us to quantify the concentrations of C-reactive protein and suppressor of tumorigenicity 2 with a detection limit of 8 and 90 pM, respectively. This device should be useful for sophisticated, parallel biochemical microfluidic processing in point-of-care settings under limited resources.
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