Increased Intrathecal B and Plasma Cells in Patients With Anti-IgLON5 Disease A Case Series

Background and Objectives Despite detection of autoantibodies, anti-IgLON5 disease was historically considered a tau-associated neurodegenerative disease, with limited treatment options and detrimental consequences for the patients. Observations in increasing case numbers hint toward underlying inflammatory mechanisms that, early detection provided, open a valuable window of opportunity for therapeutic intervention. We aimed to further substantiate this view by studying the CSF of patients with anti-IgLON5. Methods We identified 11 patients with anti-IgLON5 from our database and compared clinical, MRI, and CSF findings with a cohort of 20 patients with progressive supranuclear palsy (PSP) (as a noninflammatory tauopathy) and 22 patients with functional neurologic disorder. Results Patients with anti-IgLON5 show inflammatory changes in routine CSF analysis, an increase in B-lymphocyte frequency, and the presence of plasma cells in comparison to the PSP-control group and functional neurologic disease controls. Patients with intrathecal plasma cells showed a clinical response to rituximab. Discussion Our findings indicate the importance of inflammatory mechanisms, in particular in early and acute anti-IgLON5 cases, which may support the use of immune-suppressive treatments in these cases. The main limitation of the study is the small number of cases due to the rarity of the disease.

Automated summary

This study compared the clinical, MRI, and CSF findings of patients with anti-IgLON5 with patients with progressive supranuclear palsy (PSP) and functional neurologic disorder. The results indicate that patients with anti-IgLON5 have inflammatory changes in routine CSF analysis, an increase in B-lymphocyte frequency, and the presence of plasma cells, suggesting the importance of inflammatory mechanisms in these cases.