Intrathecal immunoglobulin synthesis in multiple sclerosis: effect of corticosteroids and azathioprine.

The objective of this study was to investigate quantitative and qualitative intrathecal IgG synthesis in 51 patients with clinically definite multiple sclerosis, taking previous immunosuppressive treatment into account. Four formulae were used to assess quantitative synthesis. Oligoclonal bands (OB) were investigated using isoelectric focusing (IEF) and silver staining. Abnormal quantitative values were detected in 42 (82%) patients, whereas OB occurred in 38 (74.5%) patients. Steroid therapy lowered quantitative synthesis in 6 out of 9 patients when given within 3 months before lumbar puncture (LP). Untreated patients with OB systematically had abnormal formulae. Patients treated with corticosteroids 10 or more months prior to LP had abnormal formulae. This fact suggests a transient depressor effect of steroids on quantitative synthesis. OB were present in patients recently treated with corticosteroids. Quantitative synthesis was higher in patients with OB than in those without OB. Azathioprine treatment did not significantly lower quantitative synthesis. We conclude that for routine purposes evaluation of intrathecal immunoglobulin synthesis could begin by performing quantitative tests. IEF seems to be mandatory for patients with normal formulae who have recently been treated with steroids.