Evaluation of a multiparametric immunofluorescence assay for standardization of neuromyelitis optica serology.
BACKGROUND
Neuromyelitis optica (NMO) is a severely disabling autoimmune disorder of the central nervous system, which predominantly affects the optic nerves and spinal cord. In a majority of cases, NMO is associated with antibodies to aquaporin-4 (AQP4) (termed NMO-IgG).


OBJECTIVE
In this study, we evaluated a new multiparametric indirect immunofluorescence (IIF) assay for NMO serology.


METHODS
Sera from 20 patients with NMO, 41 patients with multiple sclerosis (MS), 30 healthy subjects, and a commercial anti-AQP4 IgG antibody were tested in a commercial composite immunofluorescence assay ("Neurology Mosaic 17"; Euroimmun, Germany), consisting of five different diagnostic substrates (HEK cells transfected with AQP4, non-transfected HEK cells, primate cerebellum, cerebrum, and optic nerve tissue sections).


RESULTS
We identified AQP4 specific and non-specific fluorescence staining patterns and established positivity criteria. Based on these criteria, this kit yielded a high sensitivity (95%) and specificity (100%) for NMO and had a significant positive and negative likelihood ratio (LR+ = ∞, LR- = 0.05). Moreover, a 100% inter- and intra-laboratory reproducibility was found.


CONCLUSIONS
The biochip mosaic assay tested in this study is a powerful tool for NMO serology, fast to perform, highly sensitive and specific for NMO, reproducible, and suitable for inter-laboratory standardization as required for multi-centre clinical trials.
Clinical Neurobiology Unit, Regional Referring Multiple Sclerosis Centre, University Hospital San Luigi Gonzaga, Orbassano, Turin, Italy. letiziagranieri@libero.it
Letizia
L
Granieri
Fabiana
F
Marnetto
Paola
P
Valentino
Jessica
J
Frau
Agata Katia
AK
Patanella
Petra
P
Nytrova
Patrizia
P
Sola
Marco
M
Capobianco
Sven
S
Jarius
Antonio
A
Bertolotto
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods*; D005456:Fluorescent Dyes; D006801:Humans; D008297:Male; D008875:Middle Aged; D009471:Neuromyelitis Optica / Q000097:blood*
D005456:Fluorescent Dyes