[The effects of acute large dose of gamma-irradiation on immune function of mice].

AIM

To observe the effects of large dose of gamma-irradiation on immune function of mice.

METHODS

225 cleaning-grad C57 mice, weighing(20+/-2.0) g, were randomly divided into 6 groups, and treated with 0, 6, 9, 12, 15 and 20 Gy gamma-irradiation. At different times after irradiation, lymphocytes were collected and lymphocytic apoptosis and T cell subsets were analyzed by TUNEL, May-Grunwald Giemsa (MGG) staining and flow cytometry.

RESULTS

(1)At early stage(1-14) d after radiation, the apoptotic rate of peripheral blood lymphocytes increased significantly and 12 Gy radiation resulted in the highest apoptotic rate. The number of T lymphocytes and T cell subsets decreased continuously in a dose-dependent manner. CD8(+) T cells were the most sensitive in T cell subsets to irradiation. These results suggested that early severe injury might be one of the important features of immune injury caused by acute radiation. (2) One month after radiation, the apoptotic rate of lymphocytes began to decrease and T lymphocytes and their subsets recovered gradually. However, neither the lymphocytic apoptotic rate nor the number of CD3(+) T cells and CD8(+) T cells, recovered to normal level, indicating that large dose of radiation had severe remote effects on immune function.

CONCLUSION

Apoptosis of a large number of peripheral blood lymphocytes in early stage after radiation may result in sharp reduction of T cell number and late immune function depression.