Flow cytometric scoring of micronucleated reticulocytes as a possible high-throughput radiation biodosimeter.

Micronucleated reticulocyte (MN-RET) scoring by flow cytometry (FCM) has been used in assessment of the clastogenic effects of chemicals. However, its dose-response to acute whole body irradiation (WBI) at moderate dose rates remains to be established. We show that FCM scoring of MN-RET in peripheral blood from male ICR mice exposed to WBI X-ray doses of 0.5-5 Gy at a dose rate of 0.488 Gy/min exhibits a linear dose-response relationship 24, 48, and 72 hr following WBI. Parallel microscopic counting of micronucleated polychromatic erythrocytes (MN-PCE) in bone marrow smears from the same animals showed similar linear dose-response patterns at the same time points. Indeed, MN-RET and MN-PCE were highly correlated at all doses and time points. In view of the speed and accuracy of this method, in addition to the small blood sample size needed for the assay, the flow cytometric protocol for MN-RET scoring may provide a minimally-invasive, high throughput radiation biodosimeter.