Apoptosis and cellular stress induction in human leukocytes by dental X-rays

Abstract

In clinical practice, the use of ionizing radiation, such as X-rays, is of importance in diagnostic procedures. The X-ray equipment is operated by the dentist himself before, during, and after an oral cavity procedure in dental offices. The occupationally exposed personnel (POES) receive an exposure dose, causing stochastic damage that is not commonly considered but is cumulative. Due to the above, a relationship between leukopenia and exposure to X-rays has been reported. Analysing the expression of bioindicators that allow determination of the degree of homeostatic tolerance to different exposure doses is one way to diagnose cell damage caused by this. This study aimed to evaluate cell viability, the expression of Hsp70, p53, caspase 8 and 3, and morphological changes related to apoptosis in human leukocytes exposed to X-rays from dental equipment. Whole blood from healthy subjects was used and exposed to different doses of X-rays from dental diagnostic equipment (2.28 ± 0.05, 4.56 ± 0.09, 9.12 ± 0.18, and 13.69 ± 0.27 mGy). Following this, morphology was assessed by Wright's stained blood smear of whole blood leukocytes. Subsequently, leukocytes were isolated by Ficoll Histopaque gradients from whole blood, and cell viability was measured. Finally, the Western blot technique identified the leukocyte proteins Hsp70, p53, and caspases. In the observed results, a decrease in cell viability from 96.6% to 45.4% was noticed; viability decreased as the dose of X-ray exposure increased. The expression of Hsp70, p53, Caspase 8, and 3 gradually increased up to the third dose and decreased in the last dose. Likewise, morphological changes characteristic of apoptotic cell death were observed from the first dose of exposure and became more significant at higher doses. In conclusion, there is cell damage in leukocytes exposed to low doses of X-rays; this information is relevant to implementing protection mechanisms for POES that regularly use this equipment for diagnosis in the field of dentistry.