Neutrophil granulocytes in the immunopathogenesis of adenovirus pneumonia of various severity in adult patients

Neutrophilic granulocytes (NG) are the first to migrate to the site of infection, providing antiviral protection through various mechanisms: phagocytosis, degranulation, production of reactive oxygen species, synthesis of cytokines, formation of NETs and ectosomes, and may play a key role in determining the course and outcome of the disease. However, the functional activity of NG in adenovirus infection is poorly understood. Objective: to clarify the features of neutrophil granulocyte functioning in adults with community-acquired adenovirus pneumonia (CAAP) of varying severity. Materials and methods. 30 male military personnel with a confirmed diagnosis of adenovirus pneumonia (J12.0) at the age of 37(31; 40) years in the acute period — 5.5(5.0; 7.5) days from the onset of the disease, hospitalized in the Krasnodar Specialized Clinical Infectious Diseases Hospital of the Ministry of Health, were studied. Study Group 1 (SG1) consisted of 22 patients with mild pneumonia, Study Group 2 (SG2) consisted of 8 patients with severe pneumonia, and the comparison group (CG) consisted of 22 healthy volunteers aged 37(31; 40). Immunophenotyping of lymphocyte subpopulations and NG — CD64-CD16+CD32+CD11b+, CD64+CD16+CD32+CD11b+ (FC500 «Beckman Coulter», USA), phagocytic and NADPH-oxidase activity of NG was performed. Results. We have established the disorders of antimicrobial defense in patients of both groups with CAP, more pronounced in SG2: a decrease in the number of lymphocytes, NK-, T cells, T helpers and cytotoxic lymphocytes; insufficient production of IgM and IgG. In addition, we revealed an increase in the number of NG, the proportion of band-nucleated forms, changes in the ratio of NG subset and their phenotype, associated with hyperactivation, a significant increase in NADPH-oxidase activity, a decrease in the phagocytic activity of NG. Conclusion. Immune system dysfunctions in adults with CAAP are multifactorial and involve both innate and adaptive components of anti-infective immunity. In CAAP, NG are a critical component of the immune response necessary for controlling infection, but when dysregulated, they become a significant factor in pathogenesis, determining the severity of the disease and the risk of complications. This necessitates the assessment of immune status, particularly NG, and the development of immunotherapy methods.