EFFECTS OF LOW-DOSES OF X-RAYS ON THE EXPRESSION OF HUMAN CELL-SURFACE CD2 ANTIGEN IN CD2+ CHO CELLS

Thioguanine resistant CHO cells (HPRT-) were stably cotransfected with pSV2-gpt and piH3-CD2 vectors using the calcium phosphate coprecipita tion technique. The effects of single low doses of ionizing radiation were studied in a CD2+ CHO clone. The CD2+ phenotype responsible for b inding sheep erythrocytes and rosette formation, was not affected by X -rays doses in the range 2-6 cGy. However, after 10 cGy of X-irradiati on, 50% of the cells lost the CD2+ phenotype. These results suggest th at this CD2+ clone might be a very sensitive indicator of very low X-r ay doses. The implications of the phenotypic changes, observed after v ery low doses of irradiation, are discussed.