As a part of technical improvements of
chromosome aberration analysis on human peripheral lymphocytes for
biological radiation dosimetry, we examined the optimal conditions for the use of
colcemid in chromosome preparation in order to obtain enough number of cells at metaphase in the first cell division. When treated with
colcemid at concentrations below 0.01 microgram/ml from the beginning of culture, cultures harvested at 48 hours had low mitotic indices.
Colcemid treatment at 0.025 to 0.05 microgram/ml during 48 hours resulted in high mitotic indices (8 to 15%) and almost of the mitotic cells remaining in the 1st cell division, suggesting that this range of
colcemid concentration was appropriate for continuous treatment with
colcemid. We further examined the effect of
colcemid concentration on the quantitative consistency of the yields of radiation-induced
chromosome aberration. Repeated experiments showed that the yield of dicentrics and centric rings in the culture having
colcemid at 0.025 microgram/ml concentration were larger than that at 0.05 microgram/ml. These data indicate the importance of assuring the accuracy of
colcemid concentration in the lymphocyte culture for cytogenetic radiation dosimetry.