MAB416 Sigma-AldrichAnti-Interferon-β Antibody, clone A1

Recent guidelines have recommended the use of validated assays for the measurement of neutralizing antibodies (NABs) to interferon beta (IFNbeta) in patients with multiple sclerosis (MS). In an attempt of validation, we studied the analytical performance of a bioassay based on antiviral cytopathic effect (CPE) using WISH cells and the vesicular stomatitis virus (WISH/VSV CPE).

The rheumatoid synovium displays characteristics of Toll-like receptor (TLR) activation and antiviral gene expression, including production of RANTES and interferon-beta (IFNbeta). The mechanism of this activation in rheumatoid synovial tissue is unknown. This study was designed to investigate the role of the IKK-related kinase IKKepsilon and IFN regulatory factor 3 (IRF-3) in the activation of antiviral genes in rheumatoid arthritis (RA).

Multiple sclerosis (MS) patients treated with interferon-beta (IFN-beta) often form anti-IFN-beta antibodies accompanied by a reduction in IFN-beta bioavailability. The clinical effect of these antibodies remains controversial. MS patients in British Columbia, Canada, must be diagnosed and evaluated annually by neurologists in an MS clinic in order to be reimbursed for their IFN-beta prescriptions. We have identified at the UBC MS clinic a cohort of 262 patients, each having been treated with a single IFN-beta preparation more than three years, some for nearly a decade. Of 119 patients treated with Betaseron (IFN-beta1b), 18 (15.1%) were neutralizing antibody positive (NAb+) at the time of the study, whereas of 131 treated with subcutaneous Rebif (IFN-beta1a SC), 16 (12.2%) were NAb+, but none of 12 treated with intramuscular Avonex (IFN-beta1a) had detectable neutralizing antibodies. During the first two years of treatment, the relapse rate was significantly reduced from pre-treatment rates (P<0.001) and appeared to be unaffected by the subsequent NAb status. However, the relapse rates in the NAb+ patients were significantly greater than in the NAb- patients during years 3 (P<0.010) and 4 (P<0.027). Betaseron-treated NAb+ patients tended to have more relapses than NAb- patients during year 3 and this almost reached significance (P=0.056) but their relapse rate did not differ in year 4 and later. In contrast, Rebif-treated NAb+ patients tended to have more relapses in year 3 than Rebif-treated NAb- patients (P=0.074), but in year 4 they clearly (P=0.009) had more relapses than Rebif-treated NAb- patients. There was no convincing effect on progression of disability in any group.

Human IFN-beta (HuIFN-beta) is a biologically potent protein with both antiviral and antiproliferative activities. To understand better its mode of action, a number of murine mAb were developed against a recombinant (serine-17) HuIFN-beta (rHuIFN-beta ser) and screened by ELISA and neutralization of antiviral activity. The panel of antibodies, composed of both IgA and IgG immunoglobulins, were specific for HuIFN-beta and did not crossreact with HuIFN-alpha or gamma. Furthermore, three functionally distinct epitopes (designated as sites I, II, and III) were identified based on mAb neutralization of antiviral and antiproliferative activities of recombinant and natural HuIFN-beta. Antibodies directed to sites I and II neutralized the antiviral and antiproliferative activities of rHuIFN-beta ser, though the antiviral neutralization potency of the mAb to site II was approximately 10-fold less than mAb to site I. Antibodies directed to site I neutralized both recombinant and natural HuIFN-beta, although the antiviral neutralization potency was approximately 10-fold higher against rHuIFN-beta ser than the native protein. The mAb directed to site II did not demonstrate any significant neutralization of the antiviral or antiproliferative activity of natural HuIFN-beta but neutralized a recombinant HuIFN-beta containing the native sequence. Antibodies recognizing site III did not neutralize the biologic activity of either recombinant or natural HuIFN-beta. Thus, three epitopes on HuIFN-beta have been identified, two of which are associated with both antiviral and antiproliferative activities.