Dynamic Changes in AQP4-IgG Level and Immunological Markers During Protein-A Immunoadsorption Therapy for NMOSD: A Case Report and Literature Review

Front Immunol. 2021 Jul 21:12:650782. doi: 10.3389/fimmu.2021.650782. eCollection 2021.


The changes in the serum levels of aquaporin-4-IgG (AQP4-IgG), immunoglobulins, and inflammatory mediators in neuromyelitis optica spectrum disorder (NMOSD) cases treated with immunoadsorption have been rarely described in detail. Here we report a 29-year-old steroid-resistant NMOSD female with a severe disability (bilateral blindness and paraplegia) who received protein-A immunoadsorption as a rescue treatment. During the total 5 sessions, the circulating level of AQP4-IgG, immunoglobulins, and complement proteins (C3 and C4) showed a rapid and sawtooth-like decrease, and the serum AQP4-IgG titer declined from 1:320 to below the detectable limit at the end of the 3rd procedure. Of all the antibodies, IgG had the biggest removal rate (>96.1%), followed by IgM (>66.7%) and IgA (53%), while complement C3 and C4 also dropped by 73% and 65%, respectively. The reduced pro-inflammatory cytokines (interleukin-8 and tumor necrosis factor-α) and marked increased lymphocyte (T and B cell) counts were also observed. The improvement of symptoms initiated after the last session, with a low AQP4-IgG titer (1:32) persisting thereafter. Accordingly, protein-A immunoadsorption treatment could be one of the potential rescue therapies for steroid-resistant NMOSD patients with a severe disability.

Keywords: AQP4-IgG; case report; neuromyelitis optica spectrum disorder; protein-A immunoadsorption; rescue therapy.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adult
  • Aquaporin 4 / immunology*
  • Biomarkers / blood*
  • Complement C3 / immunology
  • Complement C4 / immunology
  • Female
  • Humans
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology*
  • Interleukin-8
  • Lymphocyte Count
  • Neuromyelitis Optica / blood
  • Neuromyelitis Optica / immunology
  • Neuromyelitis Optica / therapy*
  • Plasmapheresis / methods*
  • Staphylococcal Protein A / immunology*
  • Tumor Necrosis Factor-alpha / blood
  • Tumor Necrosis Factor-alpha / immunology


  • Aquaporin 4
  • Biomarkers
  • Complement C3
  • Complement C4
  • Immunoglobulin G
  • Interleukin-8
  • Staphylococcal Protein A
  • Tumor Necrosis Factor-alpha