title: Distinct modes of cell death by ionizing radiation observed in two lines of feline T-lymphocytes.
abstract: We have examined in vitro radiosensitivities and radioresponses to (60)Co gamma-rays irradiation in feline T-lymphocyte cell lines, FeT-J and FL-4. There seemed to be no significant difference in clonogenic survival between the two lines. The mean lethal dose for both was both 1.9 Gy, and surviving fraction at 2 Gy was 0.30 and 0.48 for FeT-J and FL-4 cells, respectively. However, TUNEL assay indicated much higher degrees of apoptosis induction in FeT-J cells (>40%) than in FL-4 cells (<10%) at 4 days after 15 Gy irradiation. Microscopic examination revealed a larger population of multi-nucleate cells in FL-4 cells (60.3%) than in FeT-J cells (16.0%) at 4 days after 15 Gy irradiation, suggesting that a larger ratio of mitotic catastrophe occurred in FL-4 cells. These results suggest that FeT-J is more likely to be induced into apoptosis and FL-4 is more likely to fall into mitotic catastrophe, and eventually necrosis; both of them showed a similar surviving fraction against gamma-rays. The results also indicate that FL-4 cells follow a process other than apoptosis to cell death, suggesting the presence of a regulatory mechanism that may control the relationship between mitotic catastrophe and apoptosis in feline T-lymphocytes.
authors.affiliation: Laboratory of Veterinary Radiology and Radiation Biology, Department of Veterinary Medicine, Kitasato University Graduate School of Veterinary Medicine and Animal Sciences, Towada, Aomori.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Kakizaki
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamada
authors.forename: Seiichi
authors.initials: S
authors.lastname: Wada
authors.forename: Tomoo
authors.initials: T
authors.lastname: Funayama
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sakashita
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hohdatsu
authors.forename: Tadashi
authors.initials: T
authors.lastname: Sano
authors.forename: Masahiro
authors.initials: M
authors.lastname: Natsuhori
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Ito
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D002415:Cats; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D011829:Radiation Dosage; D013601:T-Lymphocytes / Q000145:classification / Q000473:pathology* / Q000528:radiation effects*