The interferon preparations are slightly different in
that interferon beta-1b is produced in modified E. coli
cells and interferon beta-1a is produced in mammalian
cells. Both interferon beta-1b and interferon beta-1a
work similarly by reducing peripheral antigen presentation
and T-cell proliferation. Furthermore, interferon
beta may downregulate adhesion molecules at the level
of the blood brain barrier. All interferon preparations
have shown efficacy in relapse reduction and disability
outcomes. In addition, whether in phase 3 regulatory
trials or subsequent trials, interferon preparations have
shown efficacy for improving MRI outcome measures
and have indicated favorable long-term safety (Herndon
et al., 2005; Kappos et al., 2006b; Reder et al., 2010).