Neuropathy accompanying IgM lambda monoclonal gammopathy

Area of Science:

• Neurology
• Immunology
• Pathology

Background:

• Monoclonal gammopathies can be associated with neurological disorders.
• The role of humoral immunity in neuropathy pathogenesis requires further elucidation.

Observation:

• A patient with IgM lambda monoclonal gammopathy and neuropathy exhibited increased intraperiod lines in sural nerve biopsy.
• Deposits of mu-heavy and lambda-light chains were identified within the myelin sheaths.

Findings:

• Patient's serum antibodies (mu-heavy and lambda-light chains) bound to peripheral nerve myelin sheaths and CNS myelin.
• Immunoblotting confirmed specific binding to myelin-associated glycoprotein (MAG) by these antibodies.
• Other immunoglobulin isotypes also bound MAG, but less distinctly than mu and lambda chains.

Implications:

• Humoral immunity, specifically antibodies against MAG, is implicated in the neuropathy associated with IgM lambda monoclonal gammopathy.
• The monoclonal gammopathy may arise secondary to a polyclonal autoimmune response targeting MAG.
• This finding opens avenues for targeted immunotherapies in related neuropathies.