DEFA3 and COVID-19: To support our findings that the aforementioned LDNs are reminiscent of the PMN-MDSCs found in cancer and in sepsis36,37, we interrogated our scRNA-seq data and found that neutrophils, in both mild and severe COVID-19 patients, contained an immature cluster expressing CEACAM8 and DEFA3, reminiscent of emergency myelopoiesis.