PARENT SESSION
1:30 PM to 3:30 PM
Sunday, April 22, 2001
Poster Session 12 Risk Estimates/Radiation Protection
Room: Exhibition Center

(P12-149) Measurement of radiation induced apoptosis in human white blood cells using flow cytometry.

Wilkins, Ruth¹, Wilkinson, Diana¹, Kutzner, Barbara¹, Sanchez-Dardon, Jaime², McLean, Jack¹, ^{1 2}

ABSTRACT-
The Comet Assay is a sensitive method for detecting apoptosis in human white blood cells irradiated in vitro, specifically CD4⁺ and CD8⁺ T-cell fractions. Although this assay was able to detect doses as low as 0.1 Gy in CD8⁺ T-cells, it is still time intensive, requiring several days to complete. Flow cytometry is a faster alternative which takes only hours to complete. It is currently being assessed for its potential as a biological dosimeter. Using flow cytometry, apoptotic cells are detected by Annexin-V-FITC labeling of the phosphatidyl serine which presents itself on the exterior of the cell membrane during apoptosis. Using four color flow cytometry, CD4⁺ and CD8⁺ T-cells can be labeled simultaneously to determine the apoptosis in these specific cell populations. The results of this assay will be compared to the Comet Assay for measuring apoptosis. This assay can also use frozen samples, simplifying analysis for those without a flow cytometer onsite. A comparison between fresh and frozen cells will be presented. To validate this assay as a biological dosimeter, it is necessary to evaluate its capacity to detect apoptotic cells following an in vivo exposure to ionizing radiation. Blood samples taken from patients exposed to ¹³¹I for medical purposes, will be analyzed by flow cytometry both before and at various times after treatment. The effect of irradiation on white blood cells, CD4⁺ and CD8⁺ T-cells will be presented. (Supported by the Canadian Nuclear Safety Commission).

KEYWORDS: Biological Dosimetry, Apoptosis, Flow Cytometry, Human Lymphocytes