Cyclosporin A curtails the progression of free light chain synthesis in the CSF of patients with multiple sclerosis

Free light chains in the cerebrospinal fluid of patients with multiple sclerosis correlate closely with disease activity. As part of a double‐blind placebo controlled trial of immunosuppression using cyclosporin A in patients with multiple sclerosis, light chain analysis was performed on pre‐ and post‐treatment CSF samples in 19 patients, nine having received cyclosporin A and 10 placebo. The placebo treated patients showed continued immunological activity, as evidenced by an increase in both free kappa and lambda chains, but cyclosporin A treatment resulted in no change or an improvement in light chain response, indicative of suppression of continued activity. As cyclosporin A does not enter the CSF, this implies that systemic stimulation is at least partly responsible for continued disease activity in multiple sclerosis. Cyclosporin A may thus be effective in preventing the deterioration of patients with multiple sclerosis.