B cells populating the multiple sclerosis brain mature in the draining cervical lymph nodes

Area of Science:

• Neuroimmunology
• Central Nervous System (CNS) Inflammation
• B cell immunology

Background:

• Multiple sclerosis (MS) is a CNS inflammatory disease with autoimmune B cell involvement.
• The origin and maturation site of B cells within the MS CNS remain unclear.
• B cells in cerebrospinal fluid (CSF) can interact with peripheral blood, suggesting potential peripheral maturation.

Purpose of the Study:

• To investigate whether B cells populating the MS CNS mature in draining cervical lymph nodes (CLNs).
• To understand the trafficking and maturation dynamics of B cells in relation to the CNS and secondary lymphoid tissues.

Main Methods:

• High-throughput sequencing of the antibody repertoire.
• Analysis of paired tissue samples from draining cervical lymph nodes (CLNs) and the CNS.
• Comparison of B cell clones and their maturation status in different compartments.

Main Results:

• Clonally expanded B cells were detected in both CLNs and the CNS.
• Founding members of B cell clones were predominantly identified in CLNs.
• More mature B cell clones were found in both CLNs and CNS lesions, indicating migration after maturation.

Conclusions:

• B cell maturation primarily occurs in secondary lymphoid tissues outside the CNS.
• B cells traffic freely between peripheral tissues and the CNS.
• Findings may inform immunomodulatory therapies targeting B cell trafficking and intrathecal B cell populations in MS.