False positivity of anti aquaporin-4 antibodies in natalizumab-treated patients

Abstract

Background:

Neuromyelitis optica spectrum disorders (NMOSD) represent a differential diagnosis of multiple sclerosis (MS). Detection of anti-aquaporin-4 antibodies (AQP4-Ab) is the strongest argument to confirm NMOSD. Diagnosing NMOSD is a major concern because specific MS disease modifying drugs can lead to neurological worsening.

Objective:

To report the case of two natalizumab (NTZ) treated patients who presented a false positive result for AQP4-Ab.

Methods:

A retrospective analysis of NTZ-treated patients who were tested positive for AQP4-Ab in our MS center.

Results:

Two patients treated by NTZ presented a false positive result.

Conclusions:

Clinicians should be aware of potential technical issues in detecting AQP4-Ab in NTZ-treated patients leading to false positive results.