Analysis of cell kinetics after gamma-ray irradiation using an anti-BrdU monoclonal antibody

The cell cycle was analyzed using double staining with an anti-bromodeoxyuridine (BrdU) monoclonal antibody and propidium iodide (PI). Changes in cell kinetics after irradiation were compared with those seen by the conventional PI-based DNA histogram method. The effect of irradiation on cell kinetics has been studied primarily by counting G2-arrested cells. By the present BrdU method, a rapid transition from G1 to S-phase was observed within 2 h of irradiation, followed by G1 block. Cells in the S-phase progressed to G2+M where they arrested, resulting in a decreased percentage of S cells (<5%). Release of G1 block occurred after 8 h, and G2+M cells returned to G1 after >18 h. The initial G1 arrest induced by irradiation was confirmed for the first time by the present BrdU-PI double staining.