CCL17 and COVID-19: Correspondingly, immune initiation related genes (including CD1A, CD1C, CD1E, CCL17, FCER1A, FCGR2B and others) and ribosome genes were significantly downregulated in the lungs of severe COVID-19 cases as compared to healthy controls, whereas inflammatory signals (including interferon genes, CCL2, CCL4, CCL8 and others) were upregulated (Figure 4C).