| Radiation-Induced Apoptosis of Lymphocytes in Peripheral Blood |
| Yoon Kyeong Oh, Tae Bum Lee, Taek Keun Nam, Keun Hong Kee, Cheol Hee Choi |
1Department of Therapeutic Radiology, Chosun University Medical School, Gwangju, Korea. ykoh@chosun.ac.kr
2Medical Research Institute, Chosun University Medical School, Gwangju, Korea.
3Department of Pathology, Chosun University Medical School, Gwangju, Korea.
4Department of Pharmacology, Chosun University Medical School, Gwangju, Korea. |
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| ABSTRACT |
PURPOSE:
This study quantitatively evaluated the apoptosis in human peripheral blood lymphocytes using flow cytometry, and investigated the possibility of using this method, with a small amount of blood, and the time and dose dependence of radiation-induced apoptosis.
MATERIALS AND METHODS:
Peripheral blood lymphocytes were isolated from the heparinized venous blood of 11 healthy volunteers, 8 men and 3 women, with each 10 ml of blood being divided into 15 samples. The blood lymphocytes were irradiated using a linear accelerator at a dose rate of 2.4 Gy/min, to deliver doses of 0.5, 1, 2 and 5 Gy. The control samples, and irradiated cells, were maintained in culture medium for 24, 48 and 72 hours following the irradiation.
The number of apoptotic cells after the in vitro X-irradiation was measured by flow cytometry after incubation periods of 24, 48 and 72 hours. We also observed the apoptotic cells using a DNA fragmentation assay and electron microscopy.
RESULTS:
The rate of spontaneous apoptosis increased in relation to the time interval following irradiation (1.761+/-0.161, 3.563+/-0.564, 11.098+/-2.849, at 24, 48, and 72 hours). The apoptotic cells also increased in the samples irradiated with 0.5, 1, 2 and 5 Gy, in a radiation dose and time interval after irradiation manner, with the apoptosis being too great at 72 hours after irradiation. The dose-response curves were characterized by an initial steep increase in the number of apoptotic cells for irradiation doses below 2 Gy, with a flattening of the curves as the dose approached towards 5 Gy.
CONCLUSION:
The flow cytometric assay technique yielded adequate data, and required less than 1 mL of blood. The time and dose dependence of the radiation-induced apoptosis, was also shown. It is suggested that the adequate time interval required for the evaluation of apoptosis would be 24 to 48 hours after blood sampling. |
| Key Words:
Lymphocyte, Blood, Radiation, Apoptosis |
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