Peripheral Blood Mononuclear Cell Cytokine mRNA Profiles in Acute Respiratory Infection Patients.

Introduction: Respiratory infections, collectively, are one of the World's most common and serious illness groups. As recent observations have shown, the most severe courses of acute respiratory infection, often leading to death, are due to uncontrolled cytokine production (hypercytokinemia).

Methods: The study involved 364 patients with respiratory illness being treated in clinics in St. Petersburg (Russia) in 2018-2019 and 30 healthy controls. Cytokine analysis was carried out in the acute phase of illness (2-3 days from onset of initial symptoms) and in the stage of recovery (days 9-10). The research presented is devoted to the assessment of mRNA expression of specific cytokines (interleukin [IL]-1b, IL-2, IL-4, IL-6, IL-8, IL-10, IL-18, tumor necrosis factor-α [TNF-α], and interferon-λ) and MxA in whole blood leukocytes, by means of real-time polymerase chain reaction.

Results: In 70% of patients, bacterial or viral pathogens were identified, with influenza viral infections (types A and B) prevailing. Significant increases in the expression of IL-18, TNF, and IL-10 were observed, relative to controls, only with influenza viral infections. We have shown a difference in IL-6 mRNA expression in patients with bacterial or viral pathogens. No statistically significant difference was found in white blood cells IL-4 expression levels between patients and healthy controls.

Conclusion: Investigation of the nuances of systemic cytokine production, in response to specific viral and bacterial pathogens, makes it possible to assess the risks of developing hypercytokinemia during respiratory infection with agents circulating in the human population and to predict the pathogenicity and virulence of circulating threats.