Quality control for IgG-specific oligoclonal bands
In addition to cell number, differential cell image, glucose-lactate total protein determination and the Reiber diagrams for albumin, IgG, IgA and IgM, the diagnosis of oligoclonal bands (OKB) is one of the central analytical methods in liquor diagnostics. The qualitatively reliable detection of oligoclonal IgG bands in CSF by means of isoelectric focusing (IEF) should be ensured in conformity with RiliBÄK by using an appropriate CSF control.
In subacute and chronic inflammation of the central nervous system (CNS), oligoclonal bands (OKB) or different fractions of oligoclonal IgG in the gamma range occur in the CSF. In comparison to the quantitative measurements determined in the quotient diagram, the OKB show intrathecal IgG synthesis with higher sensitivity. According to the “Handbook of Clinical Neurology”, CSF IgG-OKB are considered robust and clinically implemented biomarkers (Volume 146, 2018, Pages 67-84).
The German Society for Neurology (DGN) and the German Society for CSF Diagnostics and Clinical Neurochemistry (DGLN) have defined five different patterns of findings in their guidelines regarding standardised, qualitative OKB diagnostics when parallel measurements are made in serum and CSF:
- Pattern 1: No bands visible in serum and CSF (normal findings)
- Pattern 2: Only OKB in CSF but not in serum as evidence of intrathecal IgG synthesis
- Pattern 3: Like pattern 2, but additionally identical OKB in CSF and serum as a sign of intrathecal IgG synthesis in systemic immune response
- Pattern 4: Mirrored distribution of OKB in CSF and serum without intrathecal IgG synthesis (passive filtration of IgG from blood into CSF)
- Pattern 5: No intrathecal IgG synthesis present. In isoelectric focusing, a paraprotein (monoclonal gammopathy) is split into several closely adjacent bands.
In connection with the diagnosis of oligoclonal bands, quality assurance measures for test verification are of central importance, so internal and external quality controls are essential. For the internal quality control to check the oligoclonal bands we support you with suitable quality control material for your IgG-specific IEF test (e.g. silver staining, immunoblot or immunofixation in gel). You can find further information in our quality control product overview.