Tailed nuclei and dicentric chromosomes in irradiated subjects

A study of peripheral blood smears from irradiated Chernobyl liquidators an d other subjects has shown nuclei of some lymphocytes to have a protrusion into the cytoplasm, Such abnormal nuclei are called "tailed" nuclei (TN). S ixteen main morphologic types, observed in human peripheral blood lymphocyt es, are described. The frequency of appearance of lymphocytes with TN in a group of Chernobyl liquidators was significantly higher than in control gro ups (p < 0.001, in all cases). A positive correlation was found between the TN frequency in lymphocytes and dicentric chromosomes in lymphocytes cultu red to metaphase (p < 0.001). Elevated frequencies of dicentrics, higher th an 0.1%, were found in 17 out of 22 subjects in whom the frequency of lymph ocytes with TN was 0.8% and more. Abnormalities of the TN type in lymphocyt es are likely to result from breakdown of chromosome bridges formed by dice ntrics. The TN can be considered as a possible marker of irradiation and, t herefore, their detailed study is important. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.