Cutting Edge: Hyperinflammatory Monocytes Expressing CD56 Abound in Severe COVID-19 Patients
Stefania Campana, Claudia De Pasquale, Giacomo Sidoti Migliore, Gaetana Pezzino, Riccardo Cavaliere, Emmanuele Venanzi Rullo, Giuseppe Nunnari, Gaetano Caramori, Antonio David, Irene Bonaccorsi, Teresa Pollicino, Paolo Carrega, Guido Ferlazzo
Abstract
Abstract Proinflammatory monocytes play a preponderant role in the development of a cytokine storm causing fatal consequences in coronavirus disease 2019 (COVID-19) patients, highlighting the importance of analyzing in more detail monocyte distribution in these patients. In this study, we identified an atypical monocyte subpopulation expressing CD56 molecules that showed a low level of HLA-DR and high level of l-selectin. They released higher amounts of TNF-α and IL-6 and expressed genes associated with an excessive inflammatory process. Remarkably, the frequency of CD56+ monocytes inversely correlated with that of CD16+ monocytes and a high CD56+/CD16+monocyte ratio was associated with both disease severity and mortality, as well as with serum concentration of type I IFN, a factor able to induce the appearance of CD56+ monocytes. In conclusion, severe COVID-19 is characterized by the abundance of hyperinflammatory CD56+ monocytes, which could represent a novel marker with prognostic significance and, possibly, a therapeutic target for controlling the inflammatory process occurring during COVID-19.