MxA protein assay for optimal monitoring of IFN-beta bioactivity in the treatment of MS patients.
OBJECTIVE
Myxovirus resistance protein A (MxA) can be used as a marker of the bioactivity of interferon-beta (IFN-beta) therapy. Two to forty per cent of IFN-beta-treated multiple sclerosis (MS) patients develop IFN-beta-neutralizing antibodies (NAb) with subsequent attenuation of MxA protein induction. The aim of this study was to set up a simple MxA enzyme immunoassay (EIA) for the measurement of MxA protein and to evaluate the EIA test by comparing the results with flow cytometric analysis and the measurement of NAb.


METHODS
total of 51 IFN-beta-treated relapsing-remitting MS (RRMS) patients were tested for MxA protein expression by using both MxA EIA assay and flow cytometric analysis. Thirteen patients were confirmed to be NAb-positive.


RESULTS
The correlation between EIA and flow cytometric analysis was significant with a wider range of measured levels in the EIA. Patients with NAb had low MxA levels, but in some patients, remaining MxA induction could be detected despite NAb.


CONCLUSIONS
The MxA EIA assay seems to be a practical method for large-scale analysis of the bioactivity of IFN-beta treatment.
Vallittu
A-M
AM
Department of Virology, University of Turku, Turku, Finland. anna-maija.vallittu@utu.fi
Erälinna
J-P
JP
Ilonen
J
J
Salmi
A A
AA
Waris
M
M
D000276:Adjuvants, Immunologic / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001682:Biological Availability; D019204:GTP-Binding Proteins / Q000097:blood*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D000068556:Interferon beta-1a; D000068576:Interferon beta-1b; D016899:Interferon-beta / Q000493:pharmacokinetics* / Q000627:therapeutic use; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000097:blood* / Q000188:drug therapy; D064547:Myxovirus Resistance Proteins; D011237:Predictive Value of Tests; D013997:Time Factors
D000276:Adjuvants, Immunologic; C579071:MX1 protein, human; D064547:Myxovirus Resistance Proteins; D000068576:Interferon beta-1b; D016899:Interferon-beta; D019204:GTP-Binding Proteins; D000068556:Interferon beta-1a