title: Neutralizing antibodies to interferon beta-1a and interferon beta-1b in MS patients are cross-reactive.
abstract: OBJECTIVE
  To determine whether neutralizing antibodies (NABs) to interferon beta (IFNbeta)-1a (Avonex) and IFNbeta-1b (Betaseron) cross-react.
  
  
  BACKGROUND
  A total of 38% of MS patients treated with IFNbeta-1b and 22% of those treated with IFNbeta-1a were reported to develop NABs, which could reduce the clinical efficacy of the drug.
  
  
  METHODS
  Blood from 10 MS patients was collected before and at 3 and 6 months after initiating treatment with IFNbeta-1a. ELISA was performed to detect binding antibodies to IFNbeta-1a. Sera from patients who tested positive for binding antibodies to IFNbeta-1a were then screened for NABs to IFNbeta-1a in a biologic assay based on neutralization of antiviral activity. These serum samples were subsequently tested for cross-reactivity with IFNbeta-1b both in the ELISA and the biologic assay. In the second part of the study, sera from patients who participated in the phase III IFNbeta-1b trial at the University of Maryland were examined for cross-reactivity with IFNbeta-1a in the ELISA and the biologic assay.
  
  
  RESULTS
  Of the 10 patients treated with IFNbeta-1a, three developed binding as well as NABs to IFNbeta-1a 6 months after treatment, and these antibodies cross-reacted with IFNbeta-1b both in the binding and the biologic assay. Similarly, sera from six patients with NABs to IFNbeta-1b showed cross-reactivity with IFNbeta-1a in the binding assay. Three of these six serum samples tested for neutralizing activity against IFNbeta-1a demonstrated the presence of NABs to IFNbeta-1a.
  
  
  CONCLUSIONS
  NABs to IFNbeta-1a (Avonex) and IFNbeta-1b (Betaseron) cross-react, both in the binding and the biologic assays. This suggests that switching to alternate IFNbeta preparation in patients who develop NABs may not be clinically beneficial. Studies examining cross-reactivity between NABs to IFNbeta-1a and IFNbeta-1b in a large number of patients are indicated.
authors.affiliation: Department of Neurology, University of Maryland School of Medicine, Veterans Affairs Medical Center, Baltimore, USA.
authors.forename: O A
authors.initials: OA
authors.lastname: Khan
authors.forename: S S
authors.initials: SS
authors.lastname: Dhib-Jalbut
mesh_terms: D001667:Binding, Competitive / Q000276:immunology; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007167:Immunotherapy; D016899:Interferon-beta / Q000276:immunology*; D009103:Multiple Sclerosis / Q000276:immunology* / Q000628:therapy*; D009500:Neutralization Tests; D011446:Prospective Studies
chemical_list: D016899:Interferon-beta