Evidence for formation of somatic cell hybrids in a population of irradiated cells

Experiments using two genetically marked lines of Djungarian hamster cells (DM-15 HPRT− and DH-TK−) and the technique of hybrid selection in selective HAT medium revealed viable colonies in a mixed culture irradiated with a dose of 5 Gy. The sublines grown from these colonies were examined. Chromosome analysis showed that about 45% of those cells were hybrids inheriting chromosome markers of both parent strains. Formation of radio-induced hybrids occurs as a function of time after irradiation, 6 days proving to be the optimal interval. It is postulated that radiation-induced cell fusion and formation of viable somatic cell hybrids may be essential for cell population survival in the course of tumour radiotherapy.