Objective To explore the early response of immune-related T cells in the lung tissue of mice, whose chests were exposed to gamma rays.

Methods A total of 112 C57BL/6 mice (6–8 weeks old, (20 ± 2) g) were randomly divided into 14 groups (7 irradiation groups and 7 corresponding control groups, n = 8). The irradiation groups received a single dose of chest irradiation (20 Gy) by using a ⁶⁰Co ray source. The immune cells in the lung, including white blood cells and T cell (CD3⁺) and its subtypes (CD4⁺/CD8⁺/Treg) in the lung tissue, were detected using flow cytometry at 3 h, 12 h, and 1, 2, 3, 7, and 14 days after irradiation. The t test was used to compare the two groups.

Results The leukocytes in the lung tissue of irradiated mice were significantly reduced (t=3.446–7.781, all P<0.01). The CD3⁺ T cells decreased early after irradiation (3 h–2 days; t=4.413–15.430, all P<0.01). The Treg cells (CD4⁺CD25⁺Foxp3⁺) increased significantly (t=2.813–4.406, all P<0.05). The CD4⁺ T cells decreased significantly at the early stage after irradiation (3 h and 12 h; t=5.019, 4.912; both P<0.01) and returned to the control level after one day. The CD8⁺ T cells did not change at the early stage (3 h and 12 h), decreased significantly at 1 and 3 days ( t=6.736, 4.738; both P<0.01), and increased significantly after seven days (t=7.537, 3.903; both P<0.01). The CD4⁺/CD8⁺ ratio decreased within 12 h after irradiation ( t=5.624, 4..083; both P<0.01), increased significantly at 1 and 3 days (t=13.410, 5.702; both P<0.01), and decreased again after seven days (t=5.505, 3.928; both P<0.01).

Conclusion Chest-irradiated mice showed different changes in immune-related cells in the lung tissue at the early stage after irradiation, which may be related to the damage of immune cells by radiation and the immune response produced by the body's stress response.