Analysis of human lymphocyte cell cycle kinetics in vitro by incorporation into DNA of bromodeoxyuridine.

Human lymphocytes of four donors were cultured for 40 to 76 hours and harvested at 4 hour intervals. They were analysed for the number of 1st, 2nd and 3rd division metaphases using the BrdU-Giemsa technique. All 44 hours cultures showed metaphases only in their 1st division; 2nd division metaphases began to appear in 48 hours cultures and 3rd division metaphases in 64 hours cultures. Another group of lymphocytes from 4 other donors were irradiated and harvested at 72 hours. These cultures showed a decrease in the percentage of 3rd division metaphases, accompanied by an increase in the percentage of 1st division metaphases, proportional to the irradiation dose.