The use of AQP4-antibody testing in diagnosis Thai patients with neuromyelitis optica

ABSTRACT

Background: There are several methods to detect AQP4-antibody which is essential for diagnosis neuromyelitis optica (NMO). Objective: To evaluate an accuracy of the commercially available kit compared with other available tests. Methods: One hundred and twelve patients who visited the multiple sclerosis (MS) clinic at Siriraj Hospital were tested for AQP4-antibody by cell-based assay with Sendai method (Postfix-CBA), a commercial kit (Prefix-CBA) and an indirect immunofluorescence tissue-based assay (IIF-TBA). The patients were classified to NMO, seropositive NMOSD (AQP4-pos NMOSD), seronegative NMOSD (AQP4-neg NMOSD), classic MS (CMS), atypical MS and clinical isolated syndrome (CIS). Results: Based on postfix-CBA, there were 26 NMO, 25 AQP4-pos NMOSD, 19 AQP4-neg NMOSD, 34 CMS, 4 atypical MS and 14 CIS. There were 5 (1 NMO, 2 AQP4-neg NMOSD, 2 CMS), 7 (1 NMO, 6 AQP4-pos NMOSD) and 2 patients (1 AQP4-neg NMOSD, 1 CIS) were seropositive only by CBA-kit, CBA-Sendai and IIF-TBA respectively. Sixteen patients were seropositive by both CBA but negative by IIF-TBA. Both CBA showed strong correlation. Conclusions: CBA-kit is a relatively sensitive, comparable assay to detect anti-AQP4 antibody in Thai NMO patients. Since the kit may have a few false-negative and false-positive results, a more sensitive assay is necessary for a much more proper diagnosis in the future.