A 3-PHASE PATTERN IN GROWTH, MONOCLONAL-ANTIBODY PRODUCTION, AND METABOLITE EXCHANGE IN A HYBRIDOMA BIOREACTOR CULTURE

The use of partial cubic spline data interpolation for the calculation of volumetric metabolite exchange rates suggested the existence of th ree distinct metabolic phases during bioreactor culture of a hybridoma cell line. During phase 1, a rapid amino acid uptake rate and ammonia release rate were observed. The growth rate was low and glutamine syn thetase activity fell. In phase 2, maximum growth rate and minimum glu tamine assimilation and ammonium production rates were observed. Attem pts to corroborate the apparent ammonia assimilation in this phase usi ng (NH4Cl)-N-15 resulted in low incorporation rates into alanine and g lutamine. Maximum glutamine synthetase activity took place during this period. Maximum antibody production rate was observed during phase 3 during which peaks in glutamine assimilation, ammonia release, and glu tamine synthetase activity were observed. The apparent existence of th e three phases prompted us to carry out Northern blot analysis of glut amine synthetase RNA at appropriate times during the process. This rev ealed a pattern of appearance and disappearance of mRNA consistent wit h the three phases indicated by the fermentation parameters.