PRODUCTION AND CHARACTERIZATION OF SOLUBLE MOUSE AND HUMAN INTERFERON-γ RECEPTORS (IFNγ-R) FROM INSECT CELLS

IFNγ-antagonists may have therapeutic applications in autoimmune disorders and chronic inflammations. Recombinant receptor constructs are useful as tools for the identification of antagonists in random screening programs and for structure determination and rational drug design. Furthermore a soluble form of the human IFNγ receptor could be used itself as an antagonist. The expression of the full length extracellular domains of both human and mouse IFN-γ receptors using the baculovirus-insect cell expression system was evaluated as a function of culture conditions in pilot-scale fermentations. The kinetics of IFNγ-R formation were investigated for different dissolved oxygen (DO) levels during infection with recombinant virus. Maximum receptor concentrations of ca. 10 μg/mL were observed 5 days post-infection for DO levels of 10–30% air saturation. To gain a better understanding of the infection process we probed the physiological state of Sf9 cells before and after infection (intracellular metabolite pools) and determined specific oxygen uptake rates per viable cell and per cell volume under various culture conditions.