Decreased chimeric antibody productivity of KR12H-1 transfectoma during long-term culture results from decreased antibody gene copy number.
The stability of KR12H-1 transfectoma in regard to chimeric antibody production was examined during long-term, repeated batch culture without selection pressure using antibiotics. Both serum-supplemented and serum-free media were used. Regardless of the medium used, the specific antibody productivity (q(Ab)) of transfectoma decreased by 60% to 88% during 70-day culture. This loss of antibody productivity was not due mainly to the appearance of a nonproducing population (NP) of transfectoma. The percentage of a producing population (P), which was monitored by the limiting dilution method, remained over 90% until the end of culture, indicating that the q(Ab) of P decreased during the culture. Flow cytometric data also showed the increase of cell population with low fluorescence intensity during culture, indicating that the intracellular antibody content of P decreased. The subclones of P obtained at the end of long-term culture were further characterized. Compared with the q(Ab) of P at the beginning of long-term culture, the q(Ab) of most P subclones was significantly low, confirming that the loss of antibody productivity was due mainly to the decreased q(Ab) of P during long-term culture. The decreased antibody gene copy number of P subclones was found to be partly responsible for the decreased q(Ab) of P during long-term culture. (c) 1996 John Wiley & Sons, Inc.
Kim
J H
JH
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 373-1 Kusong-Dong, Yusong-Gu, Taejon 305-701, Korea.
Bae
S W
SW
Jeong Hong
H
H
Min Lee
G
G