Neural Antibody Testing for Autoimmune Encephalitis: A Canadian Single-Centre Experience

Area of Science:

• Neuroimmunology
• Autoimmune Diseases
• Biomarker Discovery

Background:

• Neural antibodies are critical biomarkers for diagnosing autoimmune encephalitis.
• Established methods for neural antibody detection include cell-based assays (CBAs) and tissue indirect immunofluorescence (TIIF).

Purpose of the Study:

• To compare the clinical sensitivity and specificity of CBAs versus TIIF for detecting neural antibodies.
• To evaluate the utility of combined serological and cerebrospinal fluid (CSF) testing for improving diagnostic accuracy.

Main Methods:

• Retrospective review of neural antibody testing results at a single center.
• Analysis of antibodies including NMDAR, LGI1, CASPR2, AMPAR, GABA(B)R, DPPX, IgLON5, and GAD65.
• Comparison of results obtained from CBAs and TIIF in serum and CSF samples.

Main Results:

• CBAs demonstrated increased clinical sensitivity compared to TIIF for detecting neural antibodies.
• Potential for false-positive results with CBAs was observed, particularly for anti-NMDAR and CASPR2 antibodies with weak serum positivity.
• Correlation with TIIF in serum and CSF CBA/TIIF helped differentiate true-positive from false-positive results.

Conclusions:

• CBAs offer enhanced sensitivity for neural antibody detection in suspected autoimmune encephalitis.
• Confirmatory testing using TIIF in conjunction with CBA is essential for accurate diagnosis, especially in cases of weak positivity.
• Integrated testing strategies improve the reliable identification of autoimmune encephalitis.