Interferon alpha is, like IFN beta, a type 1 IFN (see section on IFN beta for explanation). They both use the same receptor, and therefore it is plausible that IFN alpha might also have a favorable impact on the course of MS.

The first large trial of recombinant IFN alpha studied 98 patients for one year in a double-blind, randomised, placebo-controlled manner; this trial showed no clear benefit. More recently, a six-month study of 20 patients was done in Italy with MRI monitoring. New or enlarging lesions occurred more often in scans of placebo-treated patients, and IFN alpha-treated patients had fewer exacerbations. The latter study used higher doses of IFN alpha than had been used in earlier trials, given by every-other-day intramuscular injection.

In the opinion of the Committee, the rationale of IFN alpha therapy is plausible and the treatment might well be effective, but larger trials are necessary to establish its safety and efficacy.