The laboratory finding most useful in the evaluation of a patient suspected to have multiple sclerosis (MS) is increased production of IgG in the central nervous system. Increased production of CSF IgG is assessed by quantifying the amount of IgG and albumin in serum and in CSF, then evaluating the level of CSF IgG, the CSF IgG index, CSF IgG synthesis rate and CSF IgG/Albumin ratio.
Oligoclonal bands are present in the CSF of approximately 90% of MS patients. A patient is considered positive for CSF oligoclonal bands if there are two or more bands in the CSF immunoglobulin region that are not present in the serum. In order to confirm local production of oligoclonal IgG in CSF, a matched serum sample is required. Oligoclonal bands present in CSF, but not in serum, indicate central nervous system production.
The albumin index is used to rule out leakage of protein into the CSF from blood, either through a damaged blood brain barrier or traumatic spinal tap. Leakage of protein from the plasma into the CSF may cause a false elevation of the IgG Index or IgG synthesis rate.
During active demyelinization, elevated levels of myelin basic protein (MBP) may be observed. Oligoclonal bands and elevated levels of CSF IgG may be present in other disease states, including meningoencephalitis, neurosyphilis, Guillain-Barré Syndrome, and meningeal carcinomatosis. Up to 10% of patients with clinically supported MS are negative for oligoclonal bands.
Oligoclonal Banding and
Multiple Sclerosis Panel 326
Multiple Sclerosis: Oligoclonal Bands in CSF in a Patient with Multiple Sclerosis