Comparison of spontaneous structural chromosome aberration frequency in 48 h-cultured human lymphocytes mitotically arrested by different colcemid treatments

Alterations in mitotic index and cell cycle kinetics are reported to be dependent on both the culture conditions and the ability of the lymphocytes of each individual to respond to phytohaemagglutinin stimulus. Thus, the frequency of structural chromosome aberrations (CA) could prove to be affected to some degree by these parameters. CA frequency and cell proliferation index (PI) were assessed in a group of healthy subjects after adding colcemid to cultured lymphocytes 3 h (standard) and 22 h (modified) before cell fixation at 48 h. All control cultures treated with colcemid for 22 h consisted exclusively of first metaphases, whereas the proportion of second-division lymphocytes in standard cultures (3 h colcemid) ranged from 4% to 49%. In addition, CA frequencies with and without gaps were always elevated in modified cultures as compared to the standard ones, and the difference between CA percentages obtained with the two methods was found to be significantly related with increasing PI values.