The sensitivity of the in vitro cytokinesis-blocked micronucleus assay in lymphocytes for different and combined radiation qualities

• Published in: Strahlentherapie und Onkologie 1998-05, Vol.174 (5), p.262-268
• Main Authors: WUTTKE, K, MÜLLER, W.-U, STREFFER, C
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Biological effects of radiation; Cell Division; Confidence Intervals; Dose-Response Relationship, Radiation; Female; Fundamental and applied biological sciences. Psychology; Humans; In Vitro Techniques; Ionizing radiations; Lymphocytes; Lymphocytes - radiation effects; Male; Micronucleus Tests - methods; Neutrons; Poisson Distribution; Sensitivity and Specificity; Tissues, organs and organisms biophysics; X-Rays
• ISSN: 0179-7158; 1439-099X
• DOI: 10.1007/bf03038719

The dose-response relationship and the relative biological effectiveness (RBE) for the induction of micronuclei in lymphocytes was analyzed after irradiation in vitro with a 6-MeV neutron beam that was followed by 240-kV X-rays. The dose range of the combined exposure comprised 1 to 3 Gy. For reference, the dose-effect relationships found after X-ray (0.5 to 5 Gy)- and neutron (0.5 to 4 Gy) exposure applied separately are presented. The possibility of an interaction between the 2 radiation qualities is investigated by the method of isobole calculation termed "envelope of additivity". Micronuclei were analyzed in PHA-stimulated, cytokinesis-blocked human lymphocytes. The dose-response relationships for the micronucleus frequencies induced by the neutron irradiation, as well as by the mixed exposure, were linear. A saturation effect was indicated after neutron doses higher than 3 Gy. After low LET exposure the dose-response curves were describable by a linear-quadratic model. For neutron-induced micronucleus frequencies, RBE-values of 2 to 3 and for the combined exposure RBE values of 1.5 to 2 were calculated for a range of effect of 0.5 to 1.5 micronuclei/binucleated lymphocyte. No indication was found for an interaction between the damage induced by X-rays and that produced by neutrons under our experimental conditions. These studies demonstrate a clear dependence of micronucleus induction on radiation quality and emphasize the usefulness of the micronucleus assay in biological dosimetry, also in cases in which high LET radiation or a mixed beam is involved as the radiation source.