ABSTRACT
At the end of March 2020, there were in excess of 800.000 confirmed cases of coronavirus disease 2019 (COVID-19) worldwide. Several reports suggest that, in severe cases, COVID-19 may cause a hyperinflammatory 'cytokine storm'. However, unlike SARS-CoV infection, high levels of anti-inflammatory mediators have also been reported in COVID-19 patients. One study reported that 16% of COVID-19 patients who died developed secondary infection, which might indicate an immune-suppressed state. We explored kinetics of mHLA-DR expression, the most widely used marker of innate immune suppression in critically ill patients, in COVID- 19 patients admitted to the ICU. Twenty-four confirmed COVID-19 patients were included, of which 75% was male and 79% had comorbidities. All patients were mechanically ventilated and exhibited large high levels of inflammatory parameters such as CRP and PCT. Although mHLA-DR expression levels in COVID-19 patients were lower than those observed in healthy subjects, the extent of suppression was less pronounced than observed in bacterial septic shock patients. mHLA-DR expression kinetics revealed no change over time. None of the COVID-19 patients developed a secondary infection. In conclusion, despite a pronounced inflammatory response, mHLA-DR expression kinetics indicate more moderate innate immune suppression in COVID-19 patients compared with bacterial septic shock patients. These data signify that innate immune suppression as a negative feedback mechanism following PAMP-induced inflammation appears less pronounced in COVID-19.