Positive effects of recombinant interferon α2b on the phenotype of CD16⁺INFα/βR1^-CD119⁺, CD16⁺INFα/βR1⁺CD119^- neutrophil granulocyte subset in patients with post-COVID syndrome and herpesvirus infections

Post-COVID syndrome (PCS) is a multisystem inflammatory condition with manifestations of chronic fatigue syndrome (CFS) and cognitive disorders (CD), along with reactivation of chronic herpesvirus infections (HVI). The PCS manifestations require studying the molecular mechanisms associated with the production of IFN and receptor functions of neutrophil granulocytes (NG), which is relevant and promotes the search for immunotherapeutic strategies in patients with PCS. Our objective was to study the in vitro effects of recombinant interferon α2b (recIFNα2b) on the phenotype of CD16⁺IFNα/βR1^-CD119⁺, CD16⁺IFNα/ βR1⁺CD119⁺ subsets and functional activity of NG in patients with post-COVID syndrome and herpesvirus infections. Materials and methods: 45 patients (24-60 years old) with PCS and HVI (HSV 1, EBV, HHV6, CMV) comprised the study group 1 (SG1). A questionnaire was conducted to assess the severity of PCS symptoms using a point scale. We performed a study of the content and phenotype of NG subsets, i.e., the CD16⁺IFNα/βR1^-CD119⁺, CD16⁺IFNα/βR1⁺CD119^-, CD16⁺IFNα/βR1⁺CD119⁺ subpopulation, phagocytic and NADPH oxidase function of NG before and after in vitro incubation with recIFNα2b (50 IU/ µL, for 60 min, at 37 °C) in the study group 1a (SG1a). The comparison group (CG) of 30 volunteers examined during the pre-COVID period. Results: We revealed more pronounced clinical manifestations of CFS and CD in SG1 patients with mixed HVI, than in mono-HVI cases. Increased expression density of all receptors was registered on CD16⁺IFNα/βR1⁺CD119^-NG and CD16⁺IFNα/βR1^-CD119⁺ NG, thus suggesting the NG activation with initiation of cytotoxicity or NETosis, a decrease in phagocytic function and intensity of NADPH oxidase activity with depletion of NG reserve capacity in SG1. We have obtained some data on the positive effect of recIFNα2b in vitro (SG1a), e.g., decreased CD16 expression density and enhancement of IFNα/βR1 receptor expression in the CD16⁺IFNα/βR1⁺CD119^- subset. In the CD16⁺IFNα/βR1^-CD119⁺ subset, we have found persistence of increased MFI CD16 and MFI CD119 receptors, restoration of defective NG phagocytic function and reduced excessive activity of NADPH oxidases. Conclusion: The positive effects of the recIFNα2b influence on deficient function of NG in PCS patients suggest an oppoptunity of using immunotherapy with a recIFNα2b-based drug, combined with highly active antioxidants for treatment of various PCS manifestations including CFS, CD, HVI, thus, probably, ensuring adequate functioning of antiviral and regulatory mechanisms of the immune system.