[Detection of oligoclonal immunoglobulins in the cerebrospinal fluid using agar gel immunoelectrophoresis with silver salt staining].

Detection of oligoclonal immunoglobulins in multiple sclerosis cerebrospinal fluid (MS-CSF) seems to be an important test in the biological diagnosis of the disease. In our laboratory, the classical agarose gel electrophoretic technic allowed the detection of CSF oligoclonal bands in only 40% of the MS patients. This relatively low percentage in comparison with those obtained by other investigators led us to develop a much more resolving electrophoretic technic: an agarose gel isoelectric focusing (IEF) with silver staining. By this method, we detected oligoclonal immunoglobulins in 43 (43%) of 100 MS-CSF exhibiting only polyclonal patterns on classical electrophoresis. Oligoclonal banding appeared particularly in patients with inflammatory type profile (36/60) according to Schuller's classification, but also in those with normal (5/26) or inflammatory transudative (2/8) type profiles. MS-CSF with oligoclonal immunoglobulins on IEF had a higher IgG/Albumin ratio (p = 0.01) than those with polyclonal immunoglobulins, while the mean IgG levels were not significantly different (p = 0.07). These results support the diagnostic usefulness of the IgG/Albumin ratio. Agarose IEF appears to be a useful technic in the detection of oligoclonal immunoglobulins and may be applied at least to CSF of patients with clinical signs of multiple sclerosis.