The use of the chemostat to study the relationship between cell growth rate, viability, and the effect of interferon on L 1210 cells

Abstract

Mouse leukemia L 1210 cells were cultivated in the chemostat at growth rates ranging from 0.1 day −1 (population doubling time ( T d ) 166.3 h) to 2.0 day −1 ( T d 8.3 h). At growth rates of 1.0 day −1 and above, the viability of the steady-state culture was greater than 99%. However, below 1.0 day −1 there was a progressive decrease in the viability of the culture with decreasing growth rate until a minimum growth rate (0.1 day −1) was reached below which steady-state cultures of L 1210 cells could not be established. Interferon treatment had no effect on the viability (>99%) of L 1210 cells cultivated at fast growth rates in the chemostat, whereas at slow growth rates (⩽0.35 day −1) interferon treatment markedly reduced the viability of the culture, even though the percentage increase in the doubling time of interferon-treated cultures was the same for cells cultivated at both fast and slow growth rates. Thus, although interferon is not directly cytotoxic, it can cause cell death by reducing the rate of cell multiplication below the minimum value compatible with viability.