Dose dependent immune and antioxidant in responses to low dose radiation

Radiotherapy is a cornerstone of cancer treatment, aiming to deliver the prescribed dose to tumor tissue while minimizing the risk of toxicity to surrounding healthy organs. Recently, low-dose radiation has gained attention for its potential biological and immunomodulatory effects. Low-dose radiation is also suggested to exert favorable biological effects; a concept often associated with radiation hormesis. This study aims to investigate the dependent impact of different low radiation doses on immune parameters and antioxidant activity. To examine this hypothesis, healthy rats were exposed to whole-body irradiation at 0.1 Gy, 0.25 Gy, and 0.5 Gy. Blood samples were collected 24 h post-irradiation to measure CD4⁺ and CD8⁺ T-cell levels using flow cytometry, while antioxidant enzymes (SOD, CAT, and GPx) were quantified spectrophotometrically. The results showed a gradual increase in immune markers with rising dose: CD4⁺ values were 31.62 ± 5.89, 39.17 ± 0.96, 49.33 ± 4.49 and 62.23 ± 0.83%, while CD8⁺ values were 29.23 ± 2.26, 32.83 ± 3.5, 46.40 ± 1.57 and 55.47 ± 2.14% for the control, 0.1 Gy, 0.25 Gy and 0.5 Gy groups respectively. Antioxidant enzymes showed an increase at 0.1 Gy (SOD: 13.46 ± 1.15, CAT: 66.98 ± 0.97, GPx: 33.28 ± 1.48 U/mL), followed by decreases at 0.25 Gy (SOD: 5.86 ± 0.56, CAT: 43.35 ± 1.93, GPx: 21.10 ± 1.30 U/mL) and 0.5 Gy (SOD: 4.18 ± 0.56, CAT: 29.45 ± 1.09, GPx: 13.57 ± 0.65 U/mL). Effect-size analysis further clarified the magnitude of biological changes across doses. Based on these findings, the observed pattern suggests a hormetic-type response under the experimental conditions, where 0.1 Gy enhances immune and antioxidant activity, while higher doses (0.25-0.5 Gy) continue to stimulate immune parameters but induce oxidative stress. These findings provide insight into dose-dependent immune and redox responses to low-dose radiation and may provide a basis for future preclinical investigations.