MICRONUCLEI AND 3AB INDEX IN X-IRRADIATED HUMAN-LYMPHOCYTES IN G0 ANDG1 PHASES

We applied the cytokinesis-block micronucleus assay to observe the rad iobiological response of human lymphocytes after X-ray treatment in th e G0 and G1 phases. In addition, we used 3-aminobenzamide (3AB) to mea sure the 3AB index in the two phases. The experimental results show th at at 2 Gy the MN yield and the 3AB index are dependent on the cell ph ase and show considerable inter-individual variability. The radiation- induced MN frequency obtained for 33 subjects is 0.470 +/- 0.063 for t he G0 phase and 0.689 +/- 0.139 for the G1 phase; the 3AB index values are 0.326 +/- 0.144 and 0.067 +/- 0.058 for G0 and G1 phases, respect ively. At the individual level, the 3AB index for the G1 phase correla tes inversely with the cytogenetic effects observed in that phase. We discuss the possibility of applying the MN test combined with the 3AB index to lymphocytes at different phases to study the individual respo nse to radiation (individual radiosensitivity).