Peculiarities of the regulation of the immune system in children residing in conditions of strontium geochemical province

There was made a study of the features of apoptosis in children drinking potable water with an increased content of stable strontium of natural origin. The percentage of non-standard samples of strontium content in the water on the observation territory was 16.7%, which corresponded to the exceedance of the maximum permissible concentration of strontium in drinking water at the level of 1.2 MPC (up to 8.4 mg/l). In children living in the strontium geochemical province, the blood content of strontium (0.1 mg/dm3) was established statistically significant higher (p = 0.02) in comparison with the results obtained from children living in the territory of relative sanitary and hygienic well-being (0.028 mg/dm³). There was made an estimation of parameters of the dependence between the concentration of strontium in drinking water and the concentration of strontium in the blood was estimated, there was obtained a reliable dependence (b₀ = 0.04, b₁ = 0.012, R² = 0.44, F = 310, p = 0.00001) of the increase in the blood content of strontium by the 1.3 times relative to the reference level from the concentration of strontium in water. In the exposure range of 7.84 ± 0.62 mg/L per 1 mg/L increase in strontium in water, its concentration in the blood was established to increase by 0.012 mg/dm3. In children living in the strontium geochemical province (1.5–0.8 times) by the method of flow cytometry, there were established to statistically significant decline the (relative and absolute values) number of CD95⁺ lymphocytes (p = 0.04-0.001) by 3.8 times, the expression of p53, bcl-2, Bax and the amount of Annexin V-FITC⁺PI^- cells dying via the path of apoptosis, as well as the content of Annexin V-FITC⁺PI⁺ cells, dying via necrosis was statistically significantly (p = 0.001) elevated, in comparison with the control group. The obtained results prove the prolonged excessive effect on the children’s organism of stable strontium supplied with drinking water to lead to changes in the functioning of the immune system, characterized by a violation of the regulation of cell death — inhibition of apoptosis and activation of necrosis. The ranges of values of strontium in the blood corresponding to the ranges at the level of 0.1 [0.04-0.11] mg/dm³ are given in the ranges of apoptotic regulation (relative content,%): CD95⁺ — 17.50 [15.48; 22.03], p53 — 0.53 [0.22; 0.98], bcl-2 0.24 [0.21; 0.36], bax = 5.66 [4.67; 7.84], AnnexinV-FITC⁺PI^- cells: 0.67 [0.56; 0.88], AnnexinV-FITC⁺ PI⁺ cells: 10.58 [9.54; 16.11]. The indices of apoptotic regulation of CD95⁺, p53, bcl-2, Annexin V-FITC⁺ PI^- are recommended to be used as indices of early disorders of the immune status, and also for the monitoring the effectiveness of preventive measures in the territories of strontium geochemical provinces.