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 b e dependent on both the culture conditions and the ability of the lymp hocytes of each individual to respond to phytohaemagglutinin stimulus. Thus, the frequency of structural chromosome aberrations (CA) could p rove to be affected to some degree by these parameters. CA frequency a nd cell proliferation index (PI) were assessed in a group of healthy s ubjects after adding colcemid to cultured lymphocytes 3 h (standard) a nd 22 h (modified) before cell fixation at 48 h. All control cultures treated with colcemid for 22 h consisted exclusively of first metaphas es, whereas the proportion of second-division lymphocytes in standard cultures (3 h colcemid) ranged from 4% to 49%. In addition, CA frequen cies with and without gaps were always elevated in modified cultures a s compared to the standard ones, and the difference between CA percent ages obtained with the two methods was found to be significantly relat ed with increasing PI values.