Background: Neutralising antibodies (NABs) against interferon beta have been described in one third of patients with multiple sclerosis treated with interferon beta. We have analysed the frequency of NABs and their clinical consequences.
Patients and methods: We have studied 68 patients. NABs were determined by protein A Myxovirus assay.
Results: Positive NABs were detected in 13% of the patients after 2 years of treatment.
Conclusions: It does not seem to exist a relationship between presence of NABs and a poor evolution of the disease in our patients with multiple sclerosis treated with beta interferon.