Activity of microbicidal systems in polymorphonuclear neutrophils during the remediation of chemical weapon destruction sites

Background: The destruction of chemical weapons stored in the Russian Federation was completed in 2017. However, remediation activities at these facilities continue, including decontamination and dismantling of process equipment, rehabilitation of buildings and sites, waste disposal and burial, and land reclamation within and around the former chemical weapon destruction facilities. Upon completion of these phases, the facilities will be subject to re-profiling or complete liquidation. Aim: The aim of the study was to examine the nonspecific immune defense of military personnel engaged in remediation activities at hazardous chemical facilities. Materials and methods: This study examined the nonspecific immunity of military personnel engaged in the remediation of chemical weapon destruction facilities at Kizner, Maradykovsky, and Leonidovka. Long-term exposure to hazardous chemicals was found to induce functional impairments in polymorphonuclear neutrophils, exhibiting a phased response pattern. Results: The oxygen-dependent microbicidal activity of neutrophils, assessed using the nitroblue tetrazolium test, was significantly lower than both the control group values and standard reference ranges, regardless of occupational roles. This indicates a functional deficiency in neutrophils and their impaired activation, possibly due to environmental and occupational stress affecting this component of the immune system. Conversely, the oxygen-independent microbicidal activity, assessed using the lysosomal-cationic test, demonstrated consistent tolerance to adverse chemical factors. Assessment of neutrophil phagocytic activity in response to Staphylococcus aureus revealed a significant decrease in the number of cells capable of engulfing foreign agents compared to the control group, whereas their functional capacity remained preserved. The proportion of phagocytic cells was not associated with the degree of exposure to toxic substances. The leukocyte migration inhibition test showed functional impairments in immunocompetent cells, indicating maladaptation, which was notable in personnel with direct exposure to toxic agents. Data from the period of active operation of chemical weapon destruction facilities exhibited no improvement in immune function markers. Conclusions: This indicates that chemical disposal operations and remediation activities at hazardous facilities place a significant strain on the immune system. This requires continued monitoring with the integration of immunological surveillance into the medical support system for personnel working at hazardous chemical facilities.