Cytokinesis blocked micronucleus (CB-MN) assay for biodosimetry of high dose accidental exposure

Background: Most of the cytogene c dosimetry, except Premature Chromosome Condensa on assay, saturates at 6 Gy. Present studies are aimed to assess feasibility of simple CB‐MN assay for prescreening of high dose accidental exposures. Materials and Methods: Human peripheral blood lymphocytes from two donors were gamma irradiated to different doses ranging from 0‐15Gy, cultured for 72 h. Cytochalasin‐B was added to the cultures at 44 h. Slides were analyzed for frequency of Mononucleated cells (MNC), ra o of Tri/Quadra nucleated cells, micronuclei ( MN ) yield in MN posi ve cells, mito c bridges and apoptosis. Results: At 5 Gy 67% Mononucleated cells, 0.22% apopto c cells and 1.76% mito c bridges were observed. Micronuclei yield in MN posi ve binucleated cells was found to be 1.43±0.04. At 8Gy 96.63% Mononucleated cells, 22.64% apopto c cells and 3.8% mito c bridges were observed. Micronuclei yield in MN posi ve binucleated cells was found to be 2.18±0.18. At 15 Gy, 99.6% of the cells were Mononucleated and 0.38% was binucleated and MN yield was 2.9 ±0. The total number of MN in MN posi ve cells increases with increasing radia on doses. Conclusion: All the three indicators number of MN in all binucleated cells (BNC) , number of MN /MN posi ve binucleated cells and the nuclear division index (NDI) can serve as good biomarkers for biodosimetry at high doses. Although the frequency of mito c bridges and apopto c bodies increases with dose, there is no consistent difference between various doses. Thus the CBMN + NDI assay can be a biodosimetry method at high doses.