Interpretation of shifts in the values of some indices of cytome analysis of buccal epithelial cells

Introduction. Accounting for micronuclei (MN) in the epithelium of the buccal mucosa is widely used to identify human exposure to genotoxic factors. Cytome analysis makes the test more sensitive to detect exposure, but it remains difficult to attribute changes in individual indices to toxicity or genotoxicity. We hypothesized that analysis of the frequencies of different forms of nuclear abnormalities in cells of different degrees of maturity could promote our understanding of the biological meaning of shifts in these indicators. Materials and methods. A cytome analysis was carried out taking into account the degree of maturity of epithelial cells in scrapings of the cheek mucosa in 6–7 years children, and, for comparison, in the urothelium of mice and rats in the control and after the administration of a cystitis inducer and the standard mutagen cyclophosphamide (CP). Results. In scrapings of the buccal mucosa from children, the frequency of cells with condensed chromatin in the nucleus, karyorrhexis and karyopyknosis increased significantly in intermediate cells, and the frequency of binuclear cells (BN), cells with nuclear buds (NB) and karyolysis increased only upon reaching a terminally differentiated state. Analysis of suspension preparations of the bladder epithelium in laboratory animals confirmed the predominant accumulation of BN in the superficial layers. In a model of cystitis in rats caused by a single administration of CP at a dose of 30 mg/kg, a decrease in the frequency of BN was observed at the end of the proliferative phase of post-traumatic epithelial regeneration (14 days after CP administration). After feeding mice with CP at a dose of 1.3 mg/kg/day for 14 days, an increase in the frequency of BN was noted among the most mature cells. Limitation of the study is the lack of assessment of the DNA content in the nuclei of epithelial cells, which did not allow evaluating forms of polyploidy other than abortive cytokinesis (endocycling and endomitosis). Conclusion. There was received confirmation of the relevance of interpretation the increase in the frequency of BNs in buccal epithelial cells in a group of exposed people as a manifestation of genotoxic effects; a decrease in the frequency of BNs in some cases may be associated with post-traumatic regeneration of the epithelium.