Evaluation of ionizing radiation sensitivity markers in a panel of lymphoid cell lines

To examine the possible associations between radiation sensitivity to doses 2 Gy, and such features of lymphoid cell responses as apoptosis, expression of apoptosis regulatory proteins (Bcl-2 family) and cell cycle progression in relation to biological dosimetry.

The cell lines examined were: Epstein Barr virus transformed lymphoid ataxia-telangiectasia (AT) cell lines, GM00717C, homozygous, and GM00736A, heterozygous, for ATM; human pro-B lymphoblastic leukaemia, Reh; murine L5178Y lymphoma sublines, LY-R and LY-S. Assays performed following X-irradiation with doses from 0.1 to 2 Gy were: terminal deoxyribonucleotidyl transferase (TdT) assay to measure apoptotic fraction, DNA content analysis by flow cytometry to assess cell cycle distribution, trypan blue exclusion test to determine cell viability, cytochalasin block micronucleus assay to assess cytogenetic damage, and Western blotting to detect proteins from the Bcl-2 family.

The cell lines in the study were of different but rather high radiation sensitivity, which was unrelated to their propensity to undergo apoptosis or micronucleus frequency. The expression of apoptotic regulatory proteins from the Bcl-2 family (constitutive and expressed 4 or 24 h after irradiation) was not related to radiation sensitivity.

None of the simple predictive tests used in the study, alone or evaluated together was suitable for detection of radiation hypersensitivity although cells known to be hypersensitive (LY-S and GM00717C) were included in the analysis.