INTERFERON INHIBITOR FACTOR PREDICTING SUCCESS OF PLASMAPHERESIS IN PATIENTS WITH MULTIPLE-SCLEROSIS

Interferons (IFN) are biological molecules with antiviral, antiprolife rative, and immunomodulatory actions. Plasmapheresis (PP) combined wit h IFN therapy in 24 multiple sclerosis (MS) patients was associated wi th a rapid increase in detectable IFN levels. We describe the presence of a detectable the efficacy of IFN therapy in these patients. We cal l this factor ''interferon inhibitor factor'' (IIF). Standard IFN assa y indicates inhibition of WISH cell protection by IFN owing to the pre sence of IIF in patient's serum. Similar results were also obtained wi th human fibroblast and human leukocyte IFNs. The best results were ob tained with an IFN mixture; results with 1:20 diluted patient's sera s howed elevation of 120% greater than 1:10 dilution. With 1:40 dilution , an elevation of 1,041% was noticed. The IIF from patient sera collec ted during PP was purified and characterized. Native gel electrophores is of IIF indicates a single protein band; further analysis on SDS gel s indicates two bands at the 200 and 21-kD range. ELISA failed to reve al the presence of any anti-IFN antibodies. This study demonstrates th e presence of IIF in MS patients' sera which are removed from the circ ulation by PP. Removal of IIF from circulation was associated with inc reased IFN levels and clinical improvement as measured by Kurtzke's di sability status scale (KDSS). (C) 1994 Wiley-Liss, Inc.