ANALYSIS OF THE RELATIONSHIP BETWEEN RADIOSENSITIVITY AND CELL AGE INPROLIFERATING MOUSE SPLEEN LYMPHOCYTES

The radiosensitivity of the first cell cycle in mouse lymphocytes was compared to that of the later cell cycles by means of analysis of chro matid-type aberrations. A nearly pure population of first-division met aphases (M1) was obtained when lymphocytes were harvested 28 h after s timulation. When the cells were fixed at 52 h of culture time, approxi mately 90% of the metaphases were composed of M2 and M3 or later cells . After irradiation with X rays 24 or 48 h after stimulation, metaphas es were scored from sequential samplings. Generally, no significant di fferences in aberration frequencies were found between cells irradiate d at the two times, indicating that the radiosensitivity of mouse lymp hocytes does not vary with their age in culture after stimulation with phytohemagglutinin. Significantly different aberration yields were ob served at different sampling times, emphasizing the necessity of seque ntial samplings when analyzing aberrations in cells irradiated during asynchronous growth. (C) 1996 by Radiation Research Society