The oxidation-reduction state of serum proteins in multiple sclerosis patients: effect of interferon beta-1b.

The concentration of reduction equivalents in serum was studied in a cohort of healthy individuals, in a group of multiple sclerosis (MS) patients undergoing treatment with interferon beta-1b and another group of MS patients who refused treatment with interferon beta-1b. Two classes of sulfhydryl groups were detectable in serum: (1) the uncovered sulfhydryls, accessible to the oxidation-reduction substrate 5,5-dithiobis-(-2-nitrobenzoic acid) (DTNB); and (2) the hidden sulfhydryls that required previous heat denaturation of serum proteins to become accessible to DTNB. The concentration of the reduced form of both the uncovered- and hidden-type of sulfhydryls was higher in the serum of MS patients than in healthy individuals. Interferon beta-1b lowered the plasma concentration of the uncovered reduced sulfhydryls after 3 months of treatment. This was in contrast to a minor effect of interferon beta-1b in the hidden-form of sulfhydryl groups. The results suggest that the concentration of reduced sulfhydryls is a biochemical marker of the in vivo oxidation/reduction reactions in MS.