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Radioadaptive response in human lymphocytes in vitro
S Venkat1, S K Apte, R C Chaubey
1Cell Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, India.
Summary
Low doses of radiation can prime human cells to resist higher doses, a phenomenon known as radioadaptive response. This adaptive response (AR) in lymphocytes varies with cell cycle stage and donor age, but not gender, and protein synthesis is not induced by gamma radiation.
Area of Science:
- Radiobiology
- Cytogenetics
- Molecular Biology
Background:
- Exposure to low doses of radiation or chemicals can induce resistance to subsequent higher doses, a phenomenon termed adaptive response (AR).
- Radioadaptive response (RAR) specifically refers to this protective effect against ionizing radiation.
- Investigating RAR in human lymphocytes is crucial for understanding cellular stress responses and radiation protection.
Purpose of the Study:
- To investigate the adaptive response (AR) to ionizing radiation in human lymphocytes.
- To determine the influence of priming dose, cell cycle stage, and donor age/gender on AR.
- To explore the molecular basis of AR by examining protein synthesis patterns under stress.
Main Methods:
- Cytogenetic analysis of human lymphocytes in whole blood cultures to assess micronuclei frequency.
- Exposure of lymphocytes to a low priming dose (adaptive dose, AD) followed by a higher challenging dose (CD) of gamma radiation.
- Analysis of protein synthesis patterns in lymphocytes subjected to mitogen, heat, or radiation stress.
Main Results:
- A low adaptive dose (AD) of approximately 1 cGy induced radioadaptive response (AR), reducing micronuclei frequency after a 100 cGy challenging dose (CD).
- An adaptive dose of 10.0 cGy did not induce AR, showing an inverse dose-response relationship.
- AR exhibited significant inter-individual variability and was dependent on cell cycle stage and donor age, with decreased AR in older individuals. No gender difference was observed.
- Gamma radiation up to 800 cGy did not significantly induce protein synthesis in human lymphocytes, contrasting with heat shock and mitogen treatments.
Conclusions:
- Human lymphocytes exhibit radioadaptive response (AR) to ionizing radiation, influenced by dose, cell cycle, and donor age.
- The lack of protein induction by gamma radiation suggests AR may involve pathways other than de novo protein synthesis.
- Further research is needed to elucidate the molecular mechanisms underlying radioadaptive response in human lymphocytes.