Given the fact that the CD1C-CD141-DCs from critical COVID-19 was largely limited to cluster1 which were characterized as immune-crosstalk quiescent, we suggested that the dysfunction of CD1C-CD141-DCs played a key role in critical COVID-19 development and prognosis, though the multi-cell communication patterns in various clusters were complicated likely involving combinatory mechanisms functionally. The gene discussed is THBD; the disease is COVID-19.