Simultaneous determination of cerebrospinal fluid oligoclonal bands and the "gamma-protein index" by agarose electrophoresis and densitometry.

Oligoclonal bands were identified in electropherograms of cerebrospinal fluid, and the "gamma-protein index" was concurrently calculated from the same strip. For the index, an upper limit of normal of 0.66 was established. We compared results with the clinical diagnosis in 69 patients with multiple sclerosis and 48 control patients with other diseases. Sensitivity, specificity, and positive predictive values of 73%, 96%, and 96%, respectively, were obtained from the index. An abnormal index and the presence of oligoclonal bands combined increased the positive predictive value to 100%. This approach may allow adequate qualitative and quantitative assessment of gamma-globulin abnormalities in cerebrospinal fluid after a single laboratory procedure.