Flow cytometric detection of gamma-H2AX to evaluate DNA damage by low dose diagnostic irradiation.

INTRODUCTION

γH2AX assay has been used for DNA damage assessment at higher doses of radiation exposure. Its expression has not been studied in cases with diagnostic low dose radiation exposure. Concerns have been raised about the after-effects of radiation in diagnostic procedures like Computed Tomography (CT) scan, Angiography etc especially when such scans are repeated within short span of time. The purpose of the present study was to assess immediate DNA damage after exposure to low level of ionizing radiation by the flow cytometric method of gamma-H2AX.

MATERIAL AND METHODS

Study sample includes total 60, cases and controls with two groups Group I-Normal controls (n = 15); Group II-Low dose, further divided in three groups: Group IIA-single CT scan (n = 15); Group IIB-Multiple CT scans (n = 15); and Group IIC-angiography single exposure (n = 15). For Low dose group blood was collected within 1 h after exposure in EDTA vaccutainers and immediately kept on ice. Lymphocytes were isolated and were fixed in 80% chilled ethanol and stored at -20 °C till further analysis. The H2AX assay was done and 10,000 cells were analysed for gamma H2AX positivity in flowcytometer.

RESULTS

Significant gamma-H2AX positivity was found in cases versus control, the most significant DNA damage amongst cases was observed in cases with multiple CT scans.

CONCLUSION

The exposure to multiple CT scans causes more double strand breaks as compared to single scan. DNA damage can be studied by flow cytometric analysis of gamma-H2AX in human peripheral lymphocytes.