Butyrate-synchronized cloned T cells retain their dependence on interleukin-2 for growth induction. A model system...

Treatment of ST2/K9 cells, a cloned mouse T-cell line, with 1 mM sodium butyrate for 24 h leads to complete growth arrest in G1. This block is completely reversible and restimulation of cellular growth is entirely dependent on the presence of interleukin-2 (Il-2) in the culture medium. Additional as yet undefined serum factors are necessary for maintenance of further proliferation. After release from butyrate-induced growth arrest, Il-2 is required only during the induction phase of DNA replication. At the onset of thymidine incorporation, the growth factor can be removed, after which DNA replication occurs and the cells are able to complete only one cycle of duplication. The data presented here show that synchronization with sodium butyrate promotes cellular accumulation in the lymphokine-sensitive phase of the cell cycle. On the basis of the parameters established for restimulation of these cells, the detailed characterization of the molecular events involved in Il-2-mediated growth is possible.