Interferon responses of leukocytes in multiple sclerosis.

In vitro interferon (IFN) responses of peripheral blood leukocytes to measles virus and to other IFN inducers were determined for multiple sclerosis patients and normal donors. The group mean IFN response to measles virus was significantly lower in patients (15 units) than in normal donors (100 units), and a greater proportion of the patients failed to exhibit a significant IFN response. This defect was not specific for measles virus and was also observed consistently in response to Newcastle disease virus, Poly(I).Poly(C), and concanavalin A. The level of IFN response was not related to the clinical stage of disease.