Oligoclonal bands

The presence of two or more bands of immunoglobulin on isoelectric focusing (IEF ) of CSF is referred to as 'oligoclonal bands' (OCBs). This CSF oligoclonal banding is only indicative of local CNS IgG production when the banding pattern in the CSF is distinct from the pattern seen in the serum. For this reason a serum sample must be sent with a CSF sample, as is done of course for the CSF:serum IgG index.

While OCBs are well known to assist in the diagnosis of multiple sclerosis it is important to recognize that they are found in many other situations with infections (subacute sclerosing panencephalitis, rubella panencephalitis, neurosyphilis, neuroborreliosis) or autoimmunity (anti-NMDA receptor encephalitis).

Although it has been suggested that in adults, where multiple sclerosis is a predominant condition that it is only necessary' to request IEF for OCB, in children it is wise to request both quantitative (CSF:serum IgG index) and qualitative (isoelectric focusing for OCB) measures to determine whether there is local CSF IgG synthesis(King, et al., 2009-10).

5 patterns are recognised:

• Normal CSF pattern polyclonal IgG
• Oligoclonal CSF normal serum pattern – consistent with MS
• Oligoclonal bands in CSF not seen in serum but some common oliogoclonal bands found in both – consitent with MS but can have other causes.
• Identical oligoclonal bands in serum and CSF – no local synthesis, pattern seen in Guillain Barre, HIV infection and other chronic inflammatory states.
• Monoclonal band in CSF and serum – myeloma or Monoclonal gammopathy of undetermined significance (MGUS).