An 85-year-old man was being assessed for multiple sclerosis. The patient's paired cerebrospinal fluid (CSF) and serum samples were sent to the clinical biochemistry laboratory for oligoclonal-band analysis by CSF isoelectric focusing/IgG immunofixation (Fig. 1). 

Isoelectric focusing/IgG immunofixation of the patient's specimens. Lane 1, serum sample; lane 1′, corresponding CSF sample.


  1. What is the interpretation for this sample?
  2. What is the differential diagnosis for multiple bands in the γ-globulin region in CSF?

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