Human blood NC/CL cells are heterogeneously presented in severe COVID-19 and correlate with disease activity.

The COVID-19 is highly heterogeneous, ranging from cases with mild disease with an almost asymptomatic carrier to severe cases in which the disease evolves rapidly. A better understanding of monocyte response during SARS-Cov-2 infection would highlight potential biomarkers and establish other possible approaches for severe cases. Here, the promising finding was that blood NC/CL subset was skewed toward NChighCLlow and NClowCLhigh clusters among the severe COVID-19 patients. The NChighCLlow cluster in severe COVID-19 displayed a distinct clinic phenotype, implying a higher 7-day disease progression rate (P=0.019) and a worse 28-day survival (P=0.026). As supported, regarding cytokine profile in context of SARS-Cov-2 infection, it was identified that circulating NC cells are proinflammatory cells most related to regulatory cells, while CL subset displayed an effective capacity to virus. These findings have implications towards optimizing evaluation in severe COVID-19, and developing strategies that target altered balance of NC/CL cell subsets.