Abstract | BACKGROUND: OBJECTIVE: To develop a bioassay for quantification and characterization of human anti-AQP4 antibodies. DESIGN, SETTING, AND PARTICIPANTS: We developed a novel bioassay for quantification and characterization of human anti-AQP4 antibodies based on high-level expression of native AQP4 (nAQP4) protein on the surface of human astroglioma cells. The test was validated in 2 independent cohorts of patients with NMO spectrum disease. RESULTS: We detected anti-nAQP4-IgG with a sensitivity of 57.9% and specificity of 100% in patients with NMO spectrum diseases, suggesting that our bioassay is at least as sensitive and specific as the gold-standard NMO- IgG assay. The anti-AQP4 antibodies belonged predominantly to the IgG1 isotype and bound with high affinity to the extracellular domain of nAQP4. Our data suggest that the autoantibody exerts pathological properties because nAQP4-IgG-positive sera induced cell death of nAQP4-expressing cells by antibody-dependent cellular natural killer cell cytotoxic effect and complement activation. Furthermore, nAQP4-IgG titers strongly correlated with in vitro cytotoxic effect. CONCLUSIONS: In NMO, this assay may help to unravel the biological function of anti-nAQP4-IgG. Our findings demonstrate the potential of bioassays to characterize biologically relevant antibodies in human autoimmune diseases.
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Authors | Sudhakar Reddy Kalluri, Zsolt Illes, Rajneesh Srivastava, Bruce Cree, Til Menge, Jeffrey L Bennett, Achim Berthele, Bernhard Hemmer |
Journal | Archives of neurology
(Arch Neurol)
Vol. 67
Issue 10
Pg. 1201-8
(Oct 2010)
ISSN: 1538-3687 [Electronic] United States |
PMID | 20937947
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- AQP4 protein, human
- Aquaporin 4
- Immunoglobulin G
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Topics |
- Adult
- Aged
- Aquaporin 4
(blood, cerebrospinal fluid, genetics, immunology)
- Biological Assay
(methods)
- Cell Line, Tumor
- Cohort Studies
- Cytotoxicity Tests, Immunologic
(methods)
- Female
- Flow Cytometry
(methods)
- Gene Expression Regulation, Neoplastic
(physiology)
- Glioma
(pathology)
- Humans
- Immunoglobulin G
(blood, cerebrospinal fluid)
- Male
- Middle Aged
- Neuromyelitis Optica
(blood, cerebrospinal fluid, immunology)
- Transfection
(methods)
- Young Adult
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