Frequency of micronuclei in lymphocytes from in vitro gamma-irradiated human peripheral blood.

The micronucleus assay technique of Högstedt was used in studies of time-response and dose-response to single acute 137Cs gamma-ray exposure of human blood in vitro. Time-response following a 2 Gy dose was examined at postradiation times 48, 72, 77, 96, and 120 hours; micronucleated lymphocyte frequencies peaked at 77 hours, dropping insignificantly at 96 hours. Unirradiated control blood showed relatively low values peaking at 77 hours. The dose-response data obtained at 77 hours with single irradiations at dose levels 0.5, 1, 2, or 4 Gy were a good fit to a linear-quadratic relationship: Y = 0.5 + 1.17D + 0.338D2 (Y, micronucleated lymphocyte percentage; D, radiation dose in Gy). The evidence obtained and the rapidity and case of assay performance give us ground to assume that the method is applicable as a initial screening test to estimate the cytogenetic effect of human exposure in vivo.