Cell Cycle Synchronization of Human T-cell Line MOLT-4 with Thymidine

Abstract

Cultures of the human T-cell line MOLT-4 were synchronized by double thymidine block. A concentration of 0.5 mM thymidine was found to be optimal and a synchronization protocol consisting of a 15-hour first thymidine block followed by a 22-hr release and a 9-hour second thymidine block yielded about 90% cells in the G1/S boundary. MOLT-4 cells which were released from the double thymidine block moved through the cell cycle in a synchronized fashion with 75% in S phase, 50% in G2+M phase and 85% in G1 phase at 10, 14-15 and 22 hours after block, respectively. A general scheme for optimal double thymidine block of cell lines in culture was presented. The likely reasons for the subsequent quick decay of synchronization which is frequently observed following the first cell cycle were discussed. Reports in literature utilizing single or double thymidine block for mammalian cell synchronization were also reviewed.