NK cells in SARS-CoV-2 infection.

In the SARS-CoV-2 virus pandemic, the questions about specific activity of this virus in induction and/or inhibition of the innate and adaptive immune response are still open. Clinical observations of the severe and critical course of infection showed the hyperinflammation and cytokine storm. In organs and tissues that are a target for viral entry the lymphocytes and monocytes are dominant cells in tissue infiltration. There are different ways and different mechanisms leading to immune response disorders. In peripheral blood in the severe and fatal course of disease lymphopenia is frequent as a poor prognosis factor. Reduced numbers of lymphocytes, mainly T cells and NK cells, are noted in the majority of these patients. The NK cells belonging to the innate immunity system are dedicated to the antiviral response due to production of interferon (IFN) and direct lysis of virus infected cells. In SARS-CoV-2 infection NK cells' activity against this pathogen is impaired based on inhibition of IFN production and functional exhaustion. The restoration of NK cell number and function might support elimination of the SARS-CoV-2 virus, increasing chances of recovery. The use of activated NK cells in SARS-CoV-2 therapy is under clinical trials.