Genotoxic changes in peripheral lymphocytes after therapeutic exposure to crude coal tar and ultraviolet radiation
Abstract
Aims. Goeckerman therapy is based on combined exposure to UV radiation (UVA, UVB) and crude coal tar (PAHs).
Some indicators suggest presence of genotoxic hazard, however, the level of genotoxic risk of the therapy has not yet been quantified sufficiently. Presented study aims to contribute to the quantification of the genotoxic risk.
Methods. The studied group consisted of patients with chronic stable plaque psoriasis treated by Goeckerman therapy (n=29).
Heparin-treated peripheral blood samples were collected one day before the first treatment and immediately after the last procedure. The lymphocytes were isolated from the blood.
The level of genotoxicity was evaluated using an alkaline version of the Comet assay which detects DNA single strand breaks (DNA-SSBs), a neutral version of the Comet assay which detects DNA double strand breaks (DNA-DSBs), and using chromosomal aberrations. Results.
The level of DNA-SSBs increased insignificantly (median; Q1-Q3): 1.4 (0.4; 0.1-1.4) vs. 2.5 (0.6; 0.3-2.7) %tDNA (P=0.11) and the level of DNA-DSBs increased significantly: 7.8 (6.5; 3.4-10.5) vs. 20.7 (19.3; 14.2-24.6) %tDNA. The level of total number of aberrated cells (P<0.001) and structurally aberrated cells (P<0.001) increased significantly.
Conclusion. The elevated levels of the DNA-DSBs and the chromosomal aberrations in the peripheral lymphocytes indicated the presence of genotoxic hazard.
However, the elevated level of the chromosomal abnormalities was below the upper level of the reference range for Czech healthy adults. Therefore, the level of genotoxic risk seems to be low.
On the other hand, it is evident that Goeckerman therapy represents a further contribution to the lifetime load of genotoxic factors.