RADIATION DOSE-DEPENDENT VARIATIONS OF MICRONUCLEI PRODUCTION IN CYTOCHALASIN B-BLOCKED HUMAN-LYMPHOCYTES

Using the cytokinesis-block technique, lymphocytes from healthy volunteers (n = 9) were evaluated for 1) the radiation dose-response curve for micronuclei (MN) expression; 2) technique variables on the yield of MN; and 3) the shortest lymphocyte incubation time required for the MN assay. We found that the best fitting of relationships between increasing MN production and increasing irradiation dose (0-4.0Gy) was the linear-quadratic model as expressed by the yield equation Y = C + alpha D + beta D-2 (P = 0.0003). When lymphocytes were irradiated in vitro with 2.0 Gy and harvested at various time intervals, MN increased during the entire 84 hr culture time. The radiation caused a division delay in lymphocyte as indicated by an increased frequency of mononucleated cells and a decreased number of mitotic indices. The data showed that a shortened culture time (60 hr) for the MN assay is possible and that binucleated cells with greater than or equal to 3 MN were found only in cells irradiated at greater than or equal to 2.0 Gy. These findings suggest that scoring of MN in lymphocytes may be a practical biological dosimeter for the rapid screening of accidental radiation exposure victims, especially when their clinical manifestations are not obvious. (C) 1994 Wiley-Liss, Inc.