The cytokines: The interferon family - Pharmaceutical Biotechnology: Concepts and Aapplications - page 233

E. coli fermentation Cellular recovery

I.B. recovery (centrifugation) Homogenization

Butanol extraction Refolding

Size exclusion chromatography Size exclusion chromatography

Formulation and filling Freeze drying

Figure 8.7 Overview of the manufacture of Betaferon, a recombinant human IFN- β produced in E. coli .
The product differs from native human IFN- β in that it is unglycosylated and cysteine residue 17 had been
replaced by a serine residue. E. coli fermentation is achieved using minimal salts/glucose media and product
accumulates intracellularly in inclusion body (IB) form. During downstream processing, the Ibs are solubilized
in butanol, with subsequent removal of this denaturant to facilitate product refolding. After two consecutive
gel-fi ltration steps, excipients are added, the product is fi lled into glass vials and freeze-dried. It exhibits a
shelf life of 18 months when stored at 2-8 C

relapses by about 30 per cent in many patients. In some instances, a sustained reduction in
the accumulation of MS brain lesions (as measured by magnetic resonance imaging) is also
observed. However, there is little evidence that IFN-β signifi cantly alters overall progression
of the disease. A summary overview of the production of one such product (Betaferon) is
presented in Figure 8.7.
The molecular mechanism by which IFN- induces its therapeutic effect is complex and not

fully understood. It is believed that the pathology of MS is linked to the activation and prolifera-
tion of T-lymphocytes specifi c for epitopes found on specifi c myelin antigens. Upon migration to
the brain, these lymphocytes trigger an infl ammatory response mediated by the production of pro-
infl ammatory cytokines, most notably IFN-

β

. The infl ammatory response,
in addition to other elements of immunity (e.g. antibodies and complement activation), results in
the destruction of myelin surrounding neuronal axons. IFN-

γ , IL-1, IL-2 and TNF- α

likely counteracts these effects, in
part at least, by inhibiting production of IFN-γ and TNF-α and hence mediating down-regulation
of the pro-infl ammatory response.

β