Related Experiment Video
Updated: Jul 20, 2026
Measuring DNA Damage and Repair in Mouse Splenocytes After Chronic In Vivo Exposure to Very Low Doses of Beta- and Gamma-Radiation
Published on: July 3, 2015
Radiation-induced bystander effects and adaptive response in murine lymphocytes
Bhavani Shankar1, Ruchi Pandey, Krishna Sainis
1Radiation Biology and Health Sciences Division, Trombay, Mumbai, India.
Insights
Irradiated lymphocytes release factors that enhance the proliferation and radioresistance of unirradiated lymphocytes, a key aspect of radiation-induced immunomodulation.
Area of Science:
- Radiation Biology
- Immunology
- Cellular Signaling
Background:
- Bystander effects in radiation biology are crucial for understanding radiation response.
- Lymphocytes play a key role in immune responses and can be affected by radiation exposure.
Purpose of the Study:
- To investigate the bystander effects of gamma radiation on murine lymphocytes.
- To determine if irradiated conditioned medium (ICM) from gamma-irradiated lymphocytes influences unirradiated lymphocyte behavior.
Main Methods:
- Murine lymphocytes were exposed to gamma radiation (0.1-1 Gy).
- Conditioned medium (ICM) was collected and applied to unirradiated lymphocytes.
- Lymphocyte proliferation was assessed using 3H-thymidine incorporation and CFSE dye dilution.
- Expression of proliferation markers (CD25, cyclin D), reactive oxygen species (ROS), nitric oxide (NO), and apoptosis were measured.
Main Results:
- ICM enhanced the proliferation of unirradiated lymphocytes in response to concanavalin A (con A), with maximal effect at 0.5 Gy.
- ICM treatment increased CD25 and cyclin D expression, along with enhanced ROS and NO generation.
- Pre-treatment with ICM conferred radioresistance to lymphocytes, an effect not blocked by a PI3K inhibitor.
Conclusions:
- Soluble factors released by irradiated lymphocytes induce a signaling cascade in unirradiated cells.
- This cascade leads to increased mitogenic response and radioresistance.
- These findings highlight the role of bystander effects in radiation-induced immunomodulation.
Purpose:
To study the bystander effects of gamma-radiation in murine lymphocytes using irradiated conditioned medium (ICM) generated from irradiated lymphocytes.
Methods:
Proliferation response of unirradiated lymphocytes to mitogen concanavalin A (con A) in presence of ICM, collected from gamma-irradiated lymphocytes (60Co source; 0.35 Gy/min; 0.1-1 Gy), was studied by 3H-thymidine incorporation and also by dye dilution using carboxyfluorescein succinimidyl ester (CFSE). Expression of proliferation markers, interleukin 2 receptor alpha chain (CD25) and cyclin D in ICM treated lymphocytes was analyzed by labeling with specific antibodies. Intracellular reactive oxygen species (ROS) and apoptosis were estimated by flow cytometry using dichlorodihydrofluorescein diacetate (H2DCFDA) and propidium iodide, respectively. Nitric oxide (NO) was measured using Griess reagent.
Results:
Proliferation response to con A in unirradiated lymphocytes was enhanced in the presence of ICM with maximum enhancement observed in the presence of 0.5 Gy ICM. Augmentation of proliferation in the presence of ICM was accompanied by an increase in CD25 and cyclin D expression, enhanced ROS and NO generation. ICM pretreated lymphocytes showed adaptive response to radiation which was not abrogated by wortmannin, a phosphatidyl inositol 3-kinase (PI3K) inhibitor.
Conclusion:
Soluble factors released from irradiated lymphocytes initiate a signaling cascade in unirradiated lymphocytes resulting in increased response to mitogen and radioresistance which may have an important role in radiation-induced immunomodulation.
