Substantial overproduction of antibodies by applying osmotic pressure and sodium butyrate

Abstract

Much of the current cell technology has enabled increased antibody production levels due to judicious nutrient feeding to raise cell densities and design better bioreactors. This study demonstrates that hybridomas can be hyperstimulated to produce higher immunoglobulin (Ig) levels by suppressing cell growth and increasing culture longevity through adaptation to higher osmolarity media and addition of sodium butyrate. Prior to adaptation, cells placed in higher osmotic pressures (350 and 400 mOsm) were severely suppressed in growth down to 25% of the control (300 mOsm), although total Ig titers achieved were similar to the control, approximately 140 mg/L. After a week of adaptation to 350 and 400 mOsm media, cell growth was not as dramatically suppressed, but considerably higher Ig levels were attained at these elevated osmolarities. The highest yield of 265 mg/L was obtained at 350 mOsm compared to 140 mg/L at 300 mOsm, while maximum viable cell numbers dropped from 35 x 105 cells/mL to 31 x 105 cells/mL and culture longevity was extended by 20 h more than the control. Sodium butyrate, known to enhance protein production in other cell types, was then supplemented at a range of concentrations between 0.01 and 0.4 mM to the 350 mOsm culture to further enhance the Ig levels. Butyrate at a concentration of 0.1 mM, in combination with osmotic pressure at 350 mOsm, further elevated the Ig levels to 350 mg/L. Concomitantly, maximum viable cell numbers were reduced to 22 x 105 cells/mL, but culture longevity was extended by 40 h in the 0.1 mM butyrate supplemented culture compared to the control condition. Specific antibody productivity, q(Mab), continued to stay high during the stationay phase and was further elevated during the decline phase: thus, overall Ig levels can be increased by 2.3 times by combining osmotic pressure and butyrate treatment.