Combined analysis of gamma-H2AX/53BP1 foci and caspase activation in lymphocyte subsets detects recent and more remote radiation exposures

TY - JOUR

T1 - Combined analysis of gamma-H2AX/53BP1 foci and caspase activation in lymphocyte subsets detects recent and more remote radiation exposures

AU - Horn, Simon

AU - Barnard, Stephen

AU - Brady, Darren

AU - Prise, Kevin M

AU - Rothkamm, Kai

PY - 2013/12

Y1 - 2013/12

N2 - Analysis of gamma-H2AX foci in blood lymphocytes is a promising approach for rapid dose estimation to support patient triage after a radiation accident but has one major drawback: the rapid decline of foci levels post-exposure cause major uncertainties in situations where the exact timing between exposure and blood sampling is unknown. To address this issue, radiation-induced apoptosis (RIA) in lymphocytes was investigated using fluorogenic inhibitors of caspases (FLICA) as an independent biomarker for radiation exposure, which may complement the gamma-H2AX assay. Ex vivo X-irradiated peripheral blood lymphocytes from 17 volunteers showed dose- and time-dependent increases in radiation-induced apoptosis over the first 3 days after exposure, albeit with considerable interindividual variation. Comparison with gamma-H2AX and 53BP1 foci counts suggested an inverse correlation between numbers of residual foci and radiation-induced apoptosis in lymphocytes at 24 h postirradiation (P = 0.007). In T-helper (CD4), T-cytotoxic (CD8) and B-cells (CD19), some significant differences in radiation induced DSBs or apoptosis were observed, however no correlation between foci and apoptosis in lymphocyte subsets was observed at 24 h postirradiation. While gamma-H2AX and 53BP1 foci were rapidly induced and then repaired after exposure, radiation-induced apoptosis did not become apparent until 24 h after exposure. Data from six volunteers with different ex vivo doses and post-exposure times were used to test the capability of the combined assay. Results show that simultaneous analysis of gamma-H2AX and radiation-induced apoptosis may provide a rapid and more accurate triage tool in situations where the delay between exposure and blood sampling is unknown compared to gamma-H2AX alone. This combined approach may improve the accuracy of dose estimations in cases where blood sampling is performed days after the radiation exposure.

AB - Analysis of gamma-H2AX foci in blood lymphocytes is a promising approach for rapid dose estimation to support patient triage after a radiation accident but has one major drawback: the rapid decline of foci levels post-exposure cause major uncertainties in situations where the exact timing between exposure and blood sampling is unknown. To address this issue, radiation-induced apoptosis (RIA) in lymphocytes was investigated using fluorogenic inhibitors of caspases (FLICA) as an independent biomarker for radiation exposure, which may complement the gamma-H2AX assay. Ex vivo X-irradiated peripheral blood lymphocytes from 17 volunteers showed dose- and time-dependent increases in radiation-induced apoptosis over the first 3 days after exposure, albeit with considerable interindividual variation. Comparison with gamma-H2AX and 53BP1 foci counts suggested an inverse correlation between numbers of residual foci and radiation-induced apoptosis in lymphocytes at 24 h postirradiation (P = 0.007). In T-helper (CD4), T-cytotoxic (CD8) and B-cells (CD19), some significant differences in radiation induced DSBs or apoptosis were observed, however no correlation between foci and apoptosis in lymphocyte subsets was observed at 24 h postirradiation. While gamma-H2AX and 53BP1 foci were rapidly induced and then repaired after exposure, radiation-induced apoptosis did not become apparent until 24 h after exposure. Data from six volunteers with different ex vivo doses and post-exposure times were used to test the capability of the combined assay. Results show that simultaneous analysis of gamma-H2AX and radiation-induced apoptosis may provide a rapid and more accurate triage tool in situations where the delay between exposure and blood sampling is unknown compared to gamma-H2AX alone. This combined approach may improve the accuracy of dose estimations in cases where blood sampling is performed days after the radiation exposure.

KW - Adult

KW - Aged

KW - Apoptosis/radiation effects

KW - Caspases/metabolism

KW - Dose-Response Relationship, Radiation

KW - Enzyme Activation/radiation effects

KW - Histones/metabolism

KW - Humans

KW - Intracellular Signaling Peptides and Proteins/metabolism

KW - Lymphocyte Subsets/cytology

KW - Middle Aged

KW - Tumor Suppressor p53-Binding Protein 1

KW - Young Adult

U2 - 10.1667/RR13342.1

DO - 10.1667/RR13342.1

M3 - SCORING: Journal article

C2 - 24219325

VL - 180

SP - 603

EP - 609

IS - 6

ER -