Neutrophil syncytia in the peripheral blood of patients with coronavirus infection (COVID-19)

Introduction. COVID-19, an infectious disease etiologically related to the coronavirus SARS-CoV-2, manifests with fever, respiratory symptoms, and lymphocytopenia. Pathogenic mechanisms of COVID-19 remain largely unclear. SARS-CoV-2 infection was found to cause the formation of multinucleated syncytia, which dominate in lung tissues and can target lymphocytes, potentially contributing to lymphocytopenia. The formation of these structures is considered to be the result of the fusogenic ability of the SARS-CoV-2 spike-like protein. The aim was to study the morphology and pathogenic significance of intercellular interactions of peripheral blood leukocytes in patients with coronavirus infection caused by SARS-CoV-2. Materials and methods. We studiedblood samples of 30 patients infected with the SARS-CoV-2 virus, who underwent treatment in the Regional Clinical Hospital No. 2, Vladivostok, in 2021–2022. The COVID-19 diagnosis was confirmed using a PCR test. Peripheral blood buffy coat samples fixed in OsO4 were embedded in white resin epoxy (Sigma-Aldrich, USA), and then ultrathin sections were prepared. Results. Against the background of the morphological leukocyte abnormality, in the