[Morphological anomalies in "tailed" lymphocyte nuclei and their connection with dicentric chromosomes in irradiated...

Lymphocyte nuclei with a narrow outgrowth into the cytoplasm ("tail") were detected on peripheral blood smears of patients exposed to ionizing radiation during the clean up after the Chernobyl meltdown (liquidators). On average, lymphocytes with tailed nuclei occurred at a frequency of 0.43% and 0.15% in exposed patients (n = 101) and healthy donors (n = 50), respectively; the difference between the samples was significant, P < 0.001. The coefficient of correlation between frequencies of lymphocytes with tailed nuclei and those with dicentric chromosomes was 0.74 (n = 27, P < 0.001). The frequency of lymphocytes with dicentric chromosomes was increased in 9 out of 10 patients, in which lymphocytes with tailed nuclei occurred at a frequency larger than 0.8%. A double-color FISH was used to localize centromeric (not more than two signals) and telomeric (not more than one signal) regions in nuclear tails. Abnormal tailed lymphocyte nuclei were assumed to result from breaking the chromosome bridges formed by the dicentric chromosomes.