FIXED-BED DIALYSIS CULTURE OF A TRANSFECTOMA CELL-LINE PRODUCING CHIMERIC FAB-FRAGMENTS WITH NUTRIENT-SPLIT-FEEDING STRATEGY

The very shear sensitive transfectoma cell line, FAB#10, producing a c himeric Fab-antibody fragment specific for the human carcinoembryonic antigen (CEA), was cultivated in fixed bed reactors where the cells we re immobilized in macroporous carriers. As the cell line had a very lo w productivity, cultures with ''process integrated product enrichment' ' were performed in a membrane dialysis bioreactor with integrated fix ed bed, where low molecular weight metabolites are removed over the me mbrane and high molecular weight products are enriched. In a new ''nut rient-split'' feeding strategy for dialysis cultures concentrated medi um was supplied directly to the fixed bed unit, whereas a buffer solut ion was used as dialysis fluid. With the dialysis technique up to 5800 mu g Fab l(-1) could be obtained, more than 10 times higher compared to fixed bed cultures without dialysis or batch cultures with suspende d cells. The ''nutrient-split''-feeding strategy reduced the amount of medium required per mg of antibody significantly.