Fig. 1

From the blood cell count curve, we noticed that there were two peaks of the absolute value of neutrophils (February 7 and February 16) and the low absolute value of lymphocytes before the peak (February 4 and February 15). In the fluctuation of these cell counts, CRP, D-dimer, PaO2, and oxygenation index all fluctuated, although the time did not coincide completely. At the second peak on February 16, IL-6 also increased significantly. It may be related to two cytokine storms. After the second cytokine storm, the absolute value of lymphocytes did not increase significantly after conventional treatment and increased after the application of convalescent plasma co-400 ml on February 20 and 21. After intravenous infusion of MSCs on February 24 and 27 and March 1, the patients could get rid of respiratory support and the symptoms of dyspnea were relieved