PF4 and COVID-19: Further analysis found that the top 10 most highly secreted cytokines (S100A12, IL16, TNFSF13, XCL2, TXLNA, PF4, IL1B, CCL3, IL12RB1 and XCL1) contributed to >99% of the inflammatory cytokine scores in COVID-19 acute necrotizing encephalopathy patients (Fig. 3d), confirming the central role that these pro-inflammatory cytokines play to establish cytokine storm.