A semiautomated isolation procedure for selecting low-serum-requiring animal cell population

Isolation of low-serum-requiring mouse-mouse hybridoma and human hybridoma cell population was done in a simple, gradual, and semiautomated selection system. It involved the addition of medium containing a lower serum level than that of the culture vessel. The rate of addition was determined by the rate of acidification of the culture medium in the vessel. Therefore, the whole population was subjected to a gradual and continuous reduction of serum level. Dilution rate was determined by the genetic potential of individual cells. Thus, the lowest-serum-requiring cells could be isolated within the shortest possible time, without the labor of repeating subculturing.