Cell killing effects of charged particles on feline T-lymphocytes

Abstract

High-LET charged particle radiations are applied to cancer therapy because of its excellent dose distribution. However, charged particle therapy has not been applied in veterinary clinics even though it is obviously useful. On the other hand, the radiation exposure of the blood cells including lymphocytes cannot be completely avoided. Damaged cells distribute to whole body, and cause the systemic reaction. Therefore, the evaluation of the sensitivity of lymphocytes to charged particles will be indispensable information to decide the dose of particle radiation therapy for veterinary application. This study aims to compare the radiosensitivities of feline T-lymphocytes (FeT-J) between low-LET ⁶⁰Co γ-rays and high-LET charged particles such as proton, helium ion and 2 kinds of carbon ions. The radiosensitivity was evaluated in terms of clonogenicity and apoptosis incidence. The clonogenicity of FeT-J decreased in the same physical dose accompany with increasing the LET. RBE and inactivation cross sections had increased as LET dependency. However, there was no difference of apoptosis induction rate at the exposure of isosurvival dose that gave 10% survival in each radiation source. In conclusion, no change of cell killing process is generated in lymphocytes by exposure to isosurvival dose of varied particle radiations. This study indicated the basic index of radioresponses of cats' cells for particle therapy applied for veterinary medicine, and the selectivity of charged particles for animal therapy would be expanded not only carbon ions.