Effects of high cell density on growth-associated monoclonal antibody production by hybridoma T0405 cells immobilized in macroporous cellulose carriers

Relationship between monoclonal antibody (MAb) productivity and growth rate, and effects of high cell density on MAb production of hybridoma T0405 cells immobilized in macroporous cellulose carriers were investigated in continuous and batch cultures. The results showing, that the specific MAb production rate increased with increasing specific growth rate in both suspended and immobilized continuous cultures indicate a positively growth-associated relationship between MAb productivity and growth rate. Moreover, the specific production rate was higher in the immobilized cell culture than that in suspended one at all dilution rates. In order to clarify these phenomena, MAb mRNA expression and cell cycle distribution were investigated in batch cultures with immobilized cells and suspended cells. RT-PCR was used for observation of MAb mRNA expression and a two-color bromode-oxyuridine (BrdU)/propidium iodide (PI) flow cytometry method for determination of cell cycle distribution. The results revealed that MAb mRNA expression reached the peak during the exponential growth phase, suggest a positively growth-associated MAb production. And the immobilized cells continued the MAb mRNA expression until dead phase, which was longer than that in suspended cells. The cell cycle distribution patterns were observed almost the same for both immobilized and suspended cells. Such results may imply that a high cell density state has positive influence on the mRNA expression and on growth-associated MAb productivity of T0405 cells.