ENHANCED SECRETORY ABILITY FOR THE HUMAN FACTOR-VIII LIGHT-CHAIN PRODUCED IN BACULOVIRUS-INFECTED INSECT CELLS

The light and truncated heavy chains of human factor VIII, expressed s eparately in baculovirus-infected insect cells, exhibited different se cretory behaviour when compared with each other and with a biologicall y active fusion molecule of the truncated heavy and light chains. The light chain was very efficiently secreted into culture medium, as judg ed by high extracellular protein levels and the absence of evidence fo r light chain retention within cells. Alternatively, proteins containi ng the heavy chain sequence were poorly secreted and appeared to be se questered within cells, suggesting that regions within the heavy chain are responsible for the low levels of secreted protein which have gen erally been observed for recombinant factor VIII.