Evaluating Longitudinal Aquaporin-4 Antibody Results

Aquaporin-4 antibodies (AQP4 Abs) have been noted by some groups to occasionally be initially negative and to fluctuate. AQP4 Ab has been proposed as a biomarker of treatment response and impending relapse. Investigators retrospectively evaluated AQP4 serum tests in 933 patients who had at least 2 test results and an initial positive result.

Of the 933 patients, 11% seroreverted to negative at a median of 1.2 years, more commonly in patients ≤20 years old and with low initial titers. For those with positive titers, AQP4 was stable in 92%. Of those retested after seroreversion, 50% returned to seropositive. Of 9308 patients with an initial negative test, 99% remained seronegative and 0.3 seroconverted to positive a median of 0.9 years after t…