STABILITY OF TRANSFECTOMAS PRODUCING CHIMERIC ANTIBODY AGAINST THE PRE-S2 SURFACE-ANTIGEN OF HEPATITIS-B VIRUS DURING A LONG-TERM CULTURE

To design the scheme of large-scale production of chimeric antibody fo r the postexposure prophylaxis of hepatitis B virus (HBV) infection, t he stability of transfectomas (H69K-1 and 6-31) in regard to antibody production was examined during a long-term, repeated fed-batch culture without selection pressure using antibiotics. Although the H69K-1 tra nsfectoma was more stable than the 6-31 transfectoma, both displayed g radual decreases in specific antibody productivity (q(Ab)) for the fir st several weeks of cultivation. During this period, q(Ab) was decreas ed by 40% to 50%. This loss of q(Ab) was due mainly to the appearance of a nonproducing population (NP) of transfectoma, which was monitored throughout the culture by flow cytometry and the limiting dilution me thod. However, an NP did not overtake the culture and was balanced wit h a producing population (P) of transfectoma, resulting in stable anti body production. The subclones of NP obtained at the end of long-term culture were further characterized by reverse transcription-polymerase chain reaction assay of the heavy and light chain mRNA. All the subcl ones of NP derived from H69K-1 transfectoma had only light chain mRNA. On the other hand, an NP in the 6-31 transfectoma culture was heterog eneous. Some subclones of NP derived from 6-31 transfectoma had only h eavy chain mRNA and other subclones had only light chain mRNA. Taken t ogether, the results obtained here suggest that selection pressure is necessary for a long-term, continuous culture, because stable antibody production in a long-term culture was achieved only after a significa nt loss of antibody productivity. Accordingly, a batch culture appears to be more appropriate for large-scale chimeric antibody production w ithout selection pressure. (C) 1995 John Wiley and Sons, Inc.