Two components in L1210 cells and their growth characterization.

L1210 cells were separated into two populations by the standardized method of mononuclear cell purification using Ficoll-Hypaque. One population (L-cells) was obtained in the usual mononuclear layer above Ficoll-Hypaque and the other (Bo-cells) was found at the bottom of the tubes below FicollHypaque. The biological characteristics of both populations were evaluated by the following parameters at every 24 hr and up to 168 hr after intraperitoneal inoculation of 10~ L1210 cells into DBA{2J mice: growth kinetics in vi\'O and ;/1 I'ltfO, viability. morphological features, cell volume.'H-thymidine (TdR) uptake, contents of protein. D A and taurine, and modal chromosome number. Protein content was generally higher in Bo-cells than in L-cells throughout the observation period. The mean cell volume of Bo-cells increased and decreased more rapidly compared with L-cells. and its was significantly larger at earlier time points and smaller at later time points. DNA content and cell proliferation patterns in ,'itro and in \'i,·o of Bo-cells showed similar changes. JH_Td R uptake was significantly higher in Bo-cells at any time point except for the last 168 hr. and taurine contents in both Land Bo-cells showed almost mirrorimage values of their respectivc'H-TdR uptakes. Viability and cytological findings did not show any specific difference between Land Bo-cells. These studies demonstrated the heterogeneity of L 1210 cells. which until now have been believed to be very homogeneous tumor cells. The correlation between cell growth pattern and effectiveness of antineoplastic agents was also discussed.