J Korean Soc Ther Radiol Oncol.  2003 Mar;21(1):75-81.

Radiation-Induced Apoptosis of Lymphocytes in Peripheral Blood

Affiliations
  • 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.

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.

Keyword

Lymphocyte; Blood; Radiation; Apoptosis

MeSH Terms

Apoptosis*
DNA Fragmentation
Female
Flow Cytometry
Healthy Volunteers
Heparin
Humans
Lymphocytes*
Male
Microscopy, Electron
Particle Accelerators
Heparin
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