Multicentre comparison of a diagnostic assay: aquaporin-4 antibodies in neuromyelitis optica.
Antibodies to cell surface central nervous system proteins help to diagnose conditions which often respond to immunotherapies. The assessment of antibody assays needs to reflect their clinical utility. We report the results of a multicentre study of aquaporin (AQP) 4 antibody (AQP4-Ab) assays in neuromyelitis optica spectrum disorders (NMOSD).



Coded samples from patients with neuromyelitis optica (NMO) or NMOSD (101) and controls (92) were tested at 15 European diagnostic centres using 21 assays including live (n=3) or fixed cell-based assays (n=10), flow cytometry (n=4), immunohistochemistry (n=3) and ELISA (n=1).



Results of tests on 92 controls identified 12assays as highly specific (0-1 false-positive results). 32 samples from 50 (64%) NMO sera and 34 from 51 (67%) NMOSD sera were positive on at least two of the 12 highly specific assays, leaving 35 patients with seronegative NMO/spectrum disorder (SD). On the basis of a combination of clinical phenotype and the highly specific assays, 66 AQP4-Ab seropositive samples were used to establish the sensitivities (51.5-100%) of all 21 assays. The specificities (85.8-100%) were based on 92 control samples and 35 seronegative NMO/SD patient samples.



The cell-based assays were most sensitive and specific overall, but immunohistochemistry or flow cytometry could be equally accurate in specialist centres. Since patients with AQP4-Ab negative NMO/SD require different management, the use of both appropriate control samples and defined seronegative NMOSD samples is essential to evaluate these assays in a clinically meaningful way. The process described here can be applied to the evaluation of other antibody assays in the newly evolving field of autoimmune neurology.
Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
Patrick
P
Waters
Clinical Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
Markus
M
Reindl
Neuroimmunology Program, Hospital Clinic and Institut d'Investigació Biomèdica August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
Albert
A
Saiz
Clinical Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
Kathrin
K
Schanda
Clinical Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
Friederike
F
Tuller
Zdravotni ustav se sidlem v Usti nad Labem, Centrum imunologie a mikrobiologie, Usti nad Labem, Czech Republic.
Vlastimil
V
Kral
Department of Neurology, Center of Clinical Neuroscience First Faculty of Medicine, General University Hospital and First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
Petra
P
Nytrova
Laboratory for CSF and Neuroimmunology, Topelex Ltd, Prague, Czech Republic.
Ondrej
O
Sobek
Department of Clinical Immunology, Odense University Hospital, Odense, Denmark.
Helle Hvilsted
HH
Nielsen
Department of Clinical Immunology, Odense University Hospital, Odense, Denmark.
Torben
T
Barington
Department of Clinical Immunology, Odense University Hospital, Odense, Denmark.
Søren T
ST
Lillevang
Institute of Clinical Research, University of Southern Denmark, Odense, Denmark Department of Neurology, University of Pécs, Pécs, Hungary.
Zsolt
Z
Illes
Euroimmun AG, Lübeck, Germany.
Kristin
K
Rentzsch
Klinikum rechts der Isar der TU München, Klinik für Neurologie, Munich, Germany.
Achim
A
Berthele
Department of Immunology and Biotechnology, University of Pécs, Pécs, Hungary.
Tímea
T
Berki
Clinical Neurobiology Unit, Neuroscience Institute Cavalieri Ottolenghi (NICO), University Hospital San Luigi Gonzaga, Regional Referring Multiple Sclerosis Centre, Orbassano, Italy.
Letizia
L
Granieri
Clinical Neurobiology Unit, Neuroscience Institute Cavalieri Ottolenghi (NICO), University Hospital San Luigi Gonzaga, Regional Referring Multiple Sclerosis Centre, Orbassano, Italy.
Antonio
A
Bertolotto
Department of Neurology, Azienda ULSS 9 Treviso, Treviso, Italy.
Bruno
B
Giometto
Department of Neurology, Azienda ULSS 9 Treviso, Treviso, Italy.
Luigi
L
Zuliani
Sanquin Diagnostic Services, Department of Immunopathology and Blood Coagulation, Amsterdam, The Netherlands.
Dörte
D
Hamann
Department of Neurology, MS Centre ErasMS, Erasmus MC, Rotterdam, The Netherlands.
E Daniëlle
ED
van Pelt
Department of Neurology, MS Centre ErasMS, Erasmus MC, Rotterdam, The Netherlands.
Rogier
R
Hintzen
Neuroimmunology Program, Hospital Clinic and Institut d'Investigació Biomèdica August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain Institute of Neurology, Medical University of Vienna, Vienna, Austria.
Romana
R
Höftberger
Servei de Neurologia-Neuroimmunologia, Centre d'Esclerosi Múltiple de Catalunya (Cemcat), Vall d'Hebron Institut de Recerca, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
Carme
C
Costa
Servei de Neurologia-Neuroimmunologia, Centre d'Esclerosi Múltiple de Catalunya (Cemcat), Vall d'Hebron Institut de Recerca, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
Manuel
M
Comabella
Servei de Neurologia-Neuroimmunologia, Centre d'Esclerosi Múltiple de Catalunya (Cemcat), Vall d'Hebron Institut de Recerca, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
Xavier
X
Montalban
Servei de Neurologia-Neuroimmunologia, Centre d'Esclerosi Múltiple de Catalunya (Cemcat), Vall d'Hebron Institut de Recerca, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
Mar
M
Tintoré
Neurology Department, Istanbul University, Cerrahpasa Medical School, Istanbul, Turkey.
Aksel
A
Siva
Neurology Department, Istanbul University, Cerrahpasa Medical School, Istanbul, Turkey.
Ayse
A
Altintas
Department of Immunology, Istanbul University, Institute of Experimental Medicine, Istanbul, Turkey.
Günnur
G
Deniz
Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
Mark
M
Woodhall
Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
Jacqueline
J
Palace
NeuroCure Clinical Research Center (NCRC), Charité Universitätsmedizin Berlin, Berlin, Germany.
Friedemann
F
Paul
Medical Faculty, Department of Neurology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
Hans-Peter
HP
Hartung
Medical Faculty, Department of Neurology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
Orhan
O
Aktas
Molecular Neuroimmunology Group, Department of Neurology, University of Heidelberg, Germany.
Sven
S
Jarius
Molecular Neuroimmunology Group, Department of Neurology, University of Heidelberg, Germany.
Brigitte
B
Wildemann
Department of Clinical Medicine, University of Bergen, Bergen, Norway Department of Neurology, Haukeland University Hospital, Bergen, Norway.
Christian
C
Vedeler
Faculty of Medecine RTH Laennec, Lyon Neurosciences Research Centre, Neuro-inflammation and Neuro-oncology Team, Lyon, France.
Anne
A
Ruiz
Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
M Isabel
MI
Leite
Department of Neurology, University Hospital of Schleswig-Holstein, Campus Lübeck, Lübeck, Germany.
Peter
P
Trillenberg
Institute for Quality Assurance, Lübeck, Germany.
Monika
M
Probst
Euroimmun AG, Lübeck, Germany.
Sandra
S
Saschenbrecker
Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
Angela
A
Vincent
Faculty of Medecine RTH Laennec, Lyon Neurosciences Research Centre, Neuro-inflammation and Neuro-oncology Team, Lyon, France.
Romain
R
Marignier
D051401:Aquaporin 4 / Q000097:blood* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D009471:Neuromyelitis Optica / Q000097:blood* / Q000276:immunology; D012680:Sensitivity and Specificity
D051401:Aquaporin 4; D001323:Autoantibodies