Possibilities of the micronucleus test as an assay in radiotherapy

After treatment of cells with mutagenic agents, chromosome material appeared in the cytoplasm. It was shown that these micronuclei were formed from acentric chromosomal fragments or from whole chromosomes. After irradiation with x-rays a good correlation between the number of micronuclei and the clonogenic survival was observed in human melanoma cells. However, this did not occur after neutron irradiation. The mechanisms of these processes were studied with a fast proliferating cell system, the pre-implanted mouse embryo, in dependence on the radiation dose and the number of mitoses after irradiation. In contrast to chromosome aberration counts, micronuclei could be determined during interphase, the test was easy to perform and only small numbers of cells were needed. In further experiments the micronuclei were determined in human tumor biopsies before and after therapeutic irradiation and in stimulated lymphocytes from patients with non-Hodgkin lymphoma who were given whole-body irradiation later. Apparently the micronucleus test could be used as a prognostic measure for radiation response