Expression of Fas and Bcl-2 and their relationship to apoptosis in spleen lymphocytes of mice irradiated with large dose 60Co γ-rays

Objective: To investigate the expressions of Fas and Bcl-2 and their significance in apoptosis of spleen lymphocyte of mice after large dose γ-ray irradiation. Methods: At 3,6,12,24 h, 3, 7, 14 and 28 d after 6-20 Gy γ-ray irradiation mice were sacrificed and their spleens were removed. The expressions of Fas and Bcl-2 oncoprotein were analysed by LSAB immunohistochemical method. Results: The expression of Fas was strongly positive at 6 h after irradiation, especially in 6-12 Gy groups. It become less obvious along with prolongation of time after irradiation and almost disappeared on d 7 after irradiation. The expression of Bcl-2 was nearly negative at 6 h after irradiation, especially in 12-20 Gy groups, and did not recover on d 28 after irradiation. Conclusion: After large dose γ-ray irradiation the expression of Fas in mouse spleen lymphocytes shows a better relationship to lymphocyte apoptosis; in other words, Fas can prompt apoptosis. On the other hand, the action of Bcl-2 is reduced or even disappeared. Both of them play an important role in spleen lymphocyte apoptosis after large dose of γ-irradiation