Response of Cultured Human Airway Epithelial Cells to X-rays and Energetic α-particles

Summary

Radon and its progeny, which emit α-particles during decay, may play an important role in inducing human lung cancer. To gain a better understanding of the biological effects of α-particles in human lung we studied the response of cultured human airway epithelial cells to X-rays and monoenergetic helium ions. Our experimental results indicated that the radiation response of primary cultures was similar to that for airway epithelial cells that were transformed with a plasmid containing an origin-defective SV40 virus. The RBE for cell inactivation determined by the ratio of D₀ for X-rays to that for 8 MeV helium ions was 1·8–2·2. The cross-section for helium ions, calculated from the D₀ value, was about 24 µm² for cells of the primary culture. This cross-section is significantly smaller than the average geometric nuclear area (∼ 180 µm²), suggesting that an average of 7·5 α-particles (8 MeV helium ions) per cell nucleus are needed to induce a lethal lesion.