TCL1A and COVID-19: Moreover, a marked decrease could be found in the proportions of LMPP (Fig. 2e), CLP (Fig. 2f), TCL1A pre-B cells (Fig. 2g), and Pro-B cells (Fig. 2h) from COVID-19 patients with severe cases when compared to the HC group (Fig. 2e–h), while only the proportion of LMPP was significantly decreased in mild cases (Fig. 2e).