Eukaryotic expression systems: a comparison.

Eukaryotic expression systems are frequently employed for the production of recombinant proteins as therapeutics as well as research tools. Most commonly used expression systems are based on stably transfected adherent CHO cells or nonadherent lymphoid cell lines. An efficient alternative is the infection of insect cells by recombinant baculoviruses. Transient expression in mammalian cells, e.g., COS cells, is often used for the production of smaller quantities of proteins. The choice of a suitable expression system depends largely on the biochemical and biological properties of the protein of interest, as well as on the nature of the planned experiments and the amount of recombinant protein required. We summarize here the expression of the cytokine human Leukemia Inhibitory Factor (hu-LIF) in five of the most commonly used systems, namely in CHO, Sp2/0, MEL, COS, and insect cells, in conjunction with an outline of the principles and characteristics of each of these expression systems. In result, the stably transfected cell lines, CHO, Sp2/0, and MEL cells, gave rise to production of fully glycosylated hu-LIF at variable product titers; incompletely glycosylated, albeit biological action hu-LIF could be rapidly produced by transient expression in COS cells or by baculovirus-mediated infection of insect cells.