cilizumab; off-label Tocilizumab treatment of patients was accompanied by increase in circulating lymphocytes. Thus, the unique pattern of immune dysregulation in severe COVID-19 is characterized by IL-6-mediated low HLA-DR expression and lymphopenia, associated with sustained cytokine production and hyper-inflammation.

Graphical Abstract

Highlights
•  Severe COVID-19 patients display immune dysregulation or macrophage activation syndrome
•  Severe respiratory failure is associated with a major decrease of HLA-DR on CD14 monocytes
•  CD4 cell and NK cell cytopenias are characteristics of severe COVID-19
•  IL-6 blocker Tocilizumab partially rescues SARS-CoV-2-associated immune dysregulation

Proper management