Hepatocyte Response to Continuous Low Dose-rate Radiation in Radioimmunotherapy Assessed by Micronucleus Assay

Abstract

The response of hepatocytes to low dose-rate irradiation was examined in mice following the injection of radio-labelled monoclonal antibody. Mice were injected intravenously with an ¹³¹I-labelled monoclonal antibody 196-14 which recognizes CA125 antigen, and the effect of continuous low dose-rate irradiation on hepatocytes was assessed using the micronucleus assay. The frequency of micronuclei increased in a dose-dependent fashion, but it was lower than the frequency induced by conventional external X-rays which was determined immediately after the irradiation. A linear quadratic model (micronucleus frequency = aD + bD² + c) showed that the value of b decreased with low dose-rate irradiation from the radiolabelled antibody. It is concluded that the micronucleus assay is useful for the evaluation of the response of hepatocytes to irradiation in radioimmunotherapy.