Expression of NKG2A Inhibitory Receptor on Cytotoxic Lymphocytes as an Indicator of Severity in Corona Virus Disease 2019 (COVID-19) Patients

Abstract

oronavirus disease 2019 (COVID-19) is an emerging viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In a few weeks the disease became a global pandemic. Studies suggested that COVID-19 disease is more severe in individuals with a weakened immune system. Cytotoxic T-cells and NK cells are required to generate an effective immune response against viruses. Patients with severe COVID-19 have significantly lower lymphocyte and higher neutrophil counts in blood. CD8+T lymphocytes and NK cells are significantly reduced in cases of severe infection compared to patients with mild infection and healthy individuals. NKG2A receptor transduces inhibitory signaling, suppressing T-cell and NK cytokine secretion and cytotoxic function. A recently proposed mechanism via which SARS-CoV-2 overrides innate immune response is by over-expressing NKG2A on CD8+T cells and NK cells, resulting in functional exhaustion of the immune response against the viral pathogen. This study aimed to assess the expression of NKG2A inhibitory receptor on CD8+T lymphocytes and NK cells in COVID-19 patients and correlate the results with the severity of the disease. This helps to understand the immunological response in COVID-19 infection and consequently the blockade of this receptor by monoclonal antibodies could be a potential therapeutic option.