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AQP4 autoantibody assay performance in clinical laboratory service.

Fryer JP, Lennon VA, Pittock SJ, Jenkins SM, Fallier-Becker P, Clardy SL, Horta E, Jedynak EA, Lucchinetti CF, Shuster EA, Weinshenker BG, Wingerchuk DM, McKeon A - Neurol Neuroimmunol Neuroinflamm (2014)

Bottom Line: Six results were suspected false-positive: M23-FACS, 2; M1-ELISA, 2; and M23-FACS, M1-FACS, and M1-CBA, 2.M1/M23-cotransfected cells expressing smaller membrane arrays of aquaporin-4 yielded fewer false- positive FACS results than M23-transfected cells.High-order arrays of M23-aquaporin-4 may yield false-positive results by binding IgG nonspecifically.

View Article: PubMed Central - PubMed

Affiliation: Departments of Laboratory Medicine and Pathology (J.P.F., V.A.L., S.J.P., E.H., E.A.J., A.M.), Neurology (V.A.L., S.J.P., S.L.C., C.F.L., B.G.W., A.M.), Immunology (V.A.L.), and Health Sciences Research (S.M.J.), College of Medicine, Mayo Clinic, Rochester, MN; Institute of Pathology and Neuropathology (P. F.-B.), University of Tubingen, Germany; Department of Neurology (E.A.S.), College of Medicine, Mayo Clinic, Jacksonville, FL; and Department of Neurology (D.M.W.), College of Medicine, Mayo Clinic, Scottsdale, AZ.

ABSTRACT

Objective: To compare performance of contemporary aquaporin-4-immunoglobulin (Ig) G assays in clinical service.

Methods: Sera from neurologic patients (4 groups) and controls were tested initially by service ELISA (recombinant human aquaporin-4, M1 isoform) and then by cell-based fluorescence assays: fixed (CBA, M1-aquaporin-4, observer-scored) and live (fluorescence-activated cell sorting [FACS], M1 and M23 aquaporin-4 isoforms). Group 1: all Mayo Clinic patients tested from January to May 2012; group 2: consecutive aquaporin-4-IgG-positive patients from September 2011 (Mayo and non-Mayo); group 3: suspected ELISA false-negatives from 2011 to 2013 (physician-reported, high likelihood of neuromyelitis optica spectrum disorders [NMOSDs] clinically); group 4: suspected ELISA false-positives (physician-reported, not NMOSD clinically).

Results: Group 1 (n = 388): M1-FACS assay performed optimally (areas under the curves: M1 = 0.64; M23 = 0.57 [p = 0.02]). Group 2 (n = 30): NMOSD clinical diagnosis was confirmed by: M23-FACS, 24; M1-FACS, 23; M1-CBA, 20; and M1-ELISA, 18. Six results were suspected false-positive: M23-FACS, 2; M1-ELISA, 2; and M23-FACS, M1-FACS, and M1-CBA, 2. Group 3 (n = 31, suspected M1-ELISA false-negatives): results were positive for 5 sera: M1-FACS, 5; M23-FACS, 3; and M1-CBA, 2. Group 4 (n = 41, suspected M1-ELISA false-positives): all negative except 1 (positive only by M1-CBA). M1/M23-cotransfected cells expressing smaller membrane arrays of aquaporin-4 yielded fewer false- positive FACS results than M23-transfected cells.

Conclusion: Aquaporin-4-transfected CBAs, particularly M1-FACS, perform optimally in aiding NMOSD serologic diagnosis. High-order arrays of M23-aquaporin-4 may yield false-positive results by binding IgG nonspecifically.

No MeSH data available.


Related in: MedlinePlus

Examples illustrating gating strategy for fluorescence-activated cell sorting (FACS)Examples include (from left to right) serum from a patient with neuromyelitis optica spectrum disorder (NMOSD) yielding positivity by both M1-FACS and M23-FACS, serum from a patient with multiple sclerosis (MS) yielding positivity by M23-FACS only, and negative serum from a patient with MS. GFP = green fluorescent protein; pos = positive; pop = population.
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Figure 1: Examples illustrating gating strategy for fluorescence-activated cell sorting (FACS)Examples include (from left to right) serum from a patient with neuromyelitis optica spectrum disorder (NMOSD) yielding positivity by both M1-FACS and M23-FACS, serum from a patient with multiple sclerosis (MS) yielding positivity by M23-FACS only, and negative serum from a patient with MS. GFP = green fluorescent protein; pos = positive; pop = population.

Mentions: Figure 1 illustrates the FACS gating strategy. Figure e-1 at Neurology.org/nn illustrates the distribution of FACS values. Positive results yielded by sera from patients with and without an NMOSD diagnosis are shown in tables 1 and 2. Multiple assays yielded positivity for all but 6 of 45 patients with NMOSDs (table 1). A single assay yielded positivity in all but 3 of 65 patients without NMOSDs (table 2).


AQP4 autoantibody assay performance in clinical laboratory service.

Fryer JP, Lennon VA, Pittock SJ, Jenkins SM, Fallier-Becker P, Clardy SL, Horta E, Jedynak EA, Lucchinetti CF, Shuster EA, Weinshenker BG, Wingerchuk DM, McKeon A - Neurol Neuroimmunol Neuroinflamm (2014)

Examples illustrating gating strategy for fluorescence-activated cell sorting (FACS)Examples include (from left to right) serum from a patient with neuromyelitis optica spectrum disorder (NMOSD) yielding positivity by both M1-FACS and M23-FACS, serum from a patient with multiple sclerosis (MS) yielding positivity by M23-FACS only, and negative serum from a patient with MS. GFP = green fluorescent protein; pos = positive; pop = population.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4202686&req=5

Figure 1: Examples illustrating gating strategy for fluorescence-activated cell sorting (FACS)Examples include (from left to right) serum from a patient with neuromyelitis optica spectrum disorder (NMOSD) yielding positivity by both M1-FACS and M23-FACS, serum from a patient with multiple sclerosis (MS) yielding positivity by M23-FACS only, and negative serum from a patient with MS. GFP = green fluorescent protein; pos = positive; pop = population.
Mentions: Figure 1 illustrates the FACS gating strategy. Figure e-1 at Neurology.org/nn illustrates the distribution of FACS values. Positive results yielded by sera from patients with and without an NMOSD diagnosis are shown in tables 1 and 2. Multiple assays yielded positivity for all but 6 of 45 patients with NMOSDs (table 1). A single assay yielded positivity in all but 3 of 65 patients without NMOSDs (table 2).

Bottom Line: Six results were suspected false-positive: M23-FACS, 2; M1-ELISA, 2; and M23-FACS, M1-FACS, and M1-CBA, 2.M1/M23-cotransfected cells expressing smaller membrane arrays of aquaporin-4 yielded fewer false- positive FACS results than M23-transfected cells.High-order arrays of M23-aquaporin-4 may yield false-positive results by binding IgG nonspecifically.

View Article: PubMed Central - PubMed

Affiliation: Departments of Laboratory Medicine and Pathology (J.P.F., V.A.L., S.J.P., E.H., E.A.J., A.M.), Neurology (V.A.L., S.J.P., S.L.C., C.F.L., B.G.W., A.M.), Immunology (V.A.L.), and Health Sciences Research (S.M.J.), College of Medicine, Mayo Clinic, Rochester, MN; Institute of Pathology and Neuropathology (P. F.-B.), University of Tubingen, Germany; Department of Neurology (E.A.S.), College of Medicine, Mayo Clinic, Jacksonville, FL; and Department of Neurology (D.M.W.), College of Medicine, Mayo Clinic, Scottsdale, AZ.

ABSTRACT

Objective: To compare performance of contemporary aquaporin-4-immunoglobulin (Ig) G assays in clinical service.

Methods: Sera from neurologic patients (4 groups) and controls were tested initially by service ELISA (recombinant human aquaporin-4, M1 isoform) and then by cell-based fluorescence assays: fixed (CBA, M1-aquaporin-4, observer-scored) and live (fluorescence-activated cell sorting [FACS], M1 and M23 aquaporin-4 isoforms). Group 1: all Mayo Clinic patients tested from January to May 2012; group 2: consecutive aquaporin-4-IgG-positive patients from September 2011 (Mayo and non-Mayo); group 3: suspected ELISA false-negatives from 2011 to 2013 (physician-reported, high likelihood of neuromyelitis optica spectrum disorders [NMOSDs] clinically); group 4: suspected ELISA false-positives (physician-reported, not NMOSD clinically).

Results: Group 1 (n = 388): M1-FACS assay performed optimally (areas under the curves: M1 = 0.64; M23 = 0.57 [p = 0.02]). Group 2 (n = 30): NMOSD clinical diagnosis was confirmed by: M23-FACS, 24; M1-FACS, 23; M1-CBA, 20; and M1-ELISA, 18. Six results were suspected false-positive: M23-FACS, 2; M1-ELISA, 2; and M23-FACS, M1-FACS, and M1-CBA, 2. Group 3 (n = 31, suspected M1-ELISA false-negatives): results were positive for 5 sera: M1-FACS, 5; M23-FACS, 3; and M1-CBA, 2. Group 4 (n = 41, suspected M1-ELISA false-positives): all negative except 1 (positive only by M1-CBA). M1/M23-cotransfected cells expressing smaller membrane arrays of aquaporin-4 yielded fewer false- positive FACS results than M23-transfected cells.

Conclusion: Aquaporin-4-transfected CBAs, particularly M1-FACS, perform optimally in aiding NMOSD serologic diagnosis. High-order arrays of M23-aquaporin-4 may yield false-positive results by binding IgG nonspecifically.

No MeSH data available.


Related in: MedlinePlus