Testing for antibodies to human aquaporin-4 by ELISA: sensitivity, specificity, and direct comparison with immunohistochemistry

J Neurol Sci. 2012 Sep 15;320(1-2):32-7. doi: 10.1016/j.jns.2012.06.002. Epub 2012 Jun 16.


Background: Several assays have been developed to detect antibodies to aquaporin-4 (NMO-IgG/AQP4-Ab). However, many of these assays require sophisticated techniques and are thus only available at specialized laboratories. This is problematic since NMO-IgG/AQP4-Ab testing has important prognostic and therapeutic implications.

Objective: To evaluate a newly developed, commercial, enzyme-linked immunosorbent assay (ELISA) for detecting NMO-IgG/AQP4-Ab.

Methods: Serum samples from 261 patients with NMO spectrum disorders (NMOSD; n=108) and controls (n=153) were tested for AQP4-Ab by using ELISA. Of these patients, 207 were tested in parallel using a standard immunohistochemical (IHC) assay.

Results: Fifty of 66 (75.8%) patients with NMO, 17/25 (68%) with LETM, 3/14 (21.4%) with ON, 2/3 (66.7%) with ON and non-extensive transverse myelitis, and 2/153 (1.3%) controls tested positive in the ELISA. Of those NMOSD patients tested by both ELISA and IHC, 10 were positive only in the ELISA and 3 exclusively in the IHC assay, suggesting that the overall sensitivity of the ELISA was higher than that of the standard IHC assay. The ELISA yielded very good intra- and inter-run reproducibility with regard to AQP4-Ab detection and good intrarun, but only moderate inter-run reproducibility with regard to AQP4-Ab quantification. Anti-AQP4 serum concentrations correlated with disease activity (p<0.00001), but did not differ between patients with NMO and patients with isolated LETM or ON.

Conclusion: The ELISA evaluated here provides a relatively sensitive and easy-to-use diagnostic tool for detecting antibodies to AQP4 and could make AQP4-Ab testing, which is of high clinical relevance, more widely available.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aquaporin 4* / blood
  • Autoantibodies* / blood
  • Biomarkers / blood
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Enzyme-Linked Immunosorbent Assay / statistics & numerical data
  • Female
  • Humans
  • Immunohistochemistry / methods*
  • Immunohistochemistry / statistics & numerical data
  • Infant
  • Male
  • Middle Aged
  • Myelitis, Transverse / blood
  • Myelitis, Transverse / diagnosis*
  • Neuromyelitis Optica / blood
  • Neuromyelitis Optica / diagnosis*
  • Optic Neuritis / blood
  • Optic Neuritis / diagnosis*
  • Predictive Value of Tests
  • Reproducibility of Results
  • Sensitivity and Specificity


  • Aquaporin 4
  • Autoantibodies
  • Biomarkers