title: Measuring and evaluating interferon beta-induced antibodies in patients with multiple sclerosis.
abstract: Administration of interferons (IFNs) may induce antibodies that interfere with therapeutic efficacy. We have optimized and validated methods for large-scale economic screening. Sera from patients with relapsing-remitting multiple sclerosis (MS) were investigated for binding antibody (BAb) by protein-G affinity-chromatography radioimmunoassay and a commercially available enzyme immunoassay (EIA). Neutralizing antibody (NAb) was investigated by cytopathic effect assays (CEA) using both fixed amount and serially diluted sera. BAb correlated with log10-transformed titres obtained by EIA (r=0.70, P<0.0001); the latter, however, failed to demonstrate low-level BAb. Comparison of clinical significance of NAb-positivity measured by biological assays with different sensitivities demonstrated an optimal odds ratio for relapse rate using 10 laboratory units (LU)/mL. Purification of IgG prior to CEA removed toxicity from toxic sera. The neutralizing capacity data correlated linearly with logl0-transformed titres obtained by a Kawade 10-to-1 LU/mL CEA (r=0.77, P<0.0001). In conclusion, neutralizing capacity CEA utilizing a fixed amount of serum predicts differences in relapse rates in IFNbeta-treated MS patients and correlates with NAb titres of the 10-to-1 LU/mL CEA. Neutralizing capacity CEA is less laborious and more economical than titre-based NAb assays and suitable for large-scale screenings of MS patients.
authors.affiliation: Institute for Inflammation Research, Rigshospitalet University Hospital, Copenhagen, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Ross
authors.forename: K M
authors.initials: KM
authors.lastname: Clemmesen
authors.forename: P S
authors.initials: PS
authors.lastname: Sørensen
authors.forename: N
authors.initials: N
authors.lastname: Koch-Henriksen
authors.forename: K
authors.initials: K
authors.lastname: Bendtzen
mesh_terms: D000906:Antibodies / Q000097:blood; D000917:Antibody Formation; D016207:Cytokines / Q000097:blood; D006801:Humans; D000068556:Interferon beta-1a; D000068576:Interferon beta-1b; D016899:Interferon-beta / Q000276:immunology*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000097:blood / Q000276:immunology*; D009500:Neutralization Tests; D011863:Radioimmunoassay
chemical_list: D000906:Antibodies; D016207:Cytokines; D000068576:Interferon beta-1b; D016899:Interferon-beta; D000068556:Interferon beta-1a