Expression of recombinant antibody and secreted alkaline phosphatase in mammalian cells. Influence of cell line and culture system upon production kinetics

The growth and productivity of an Sp2/0 cell line, F3b10, expressing a recombinant antibody (rAb) and BHK21 cells expressing either the same rAb from the same plasmids (BHK.IgG) or secreted alkaline phosphatase (SEAP) (BHK.SEAP) were investigated. The F3b10 line was grown as a single cell suspension. The BHK lines were grown either as suspended natural aggregates or on Cytodex 3 microcarriers. The data for F3b10 showed that the cell-specific rAb production rate (QsrAb) increased in parallel with increases in the specific growth rate (μ). A similar result was obtained for suspended aggregate cultures of both recombinant BHK cell lines. In contrast, for microcarrier cultures of both BHK cell lines, Qsproduct increased as μ decreased. This report shows that the relationship between cell growth and Qsproduct for the cell lines and products studied is dependent upon the culture process. In systems where recombinant cells are growing as a single cell suspension or within a natural suspension aggregate, Qsproduct increased with increases in μ. In such systems, the cells have a rounded morphology. When cells were grown on microcarriers, Qsproduct decreased as μ increased. Cells growing attached to a surface are flat and elongated. The observed differences in the relationship of Qsproduct to μ are correlated with changes in cell morphology. The relationship between Qsproduct and μ is also affected by the choice of cell line.