MPO and COVID-19: Many other soluble markers are consistently high in MIS-C patients when compared to healthy controls or COVID-19 patients, including cytokines IL-2, IL-2RA, IL-15, IL-and 17A, cytokine receptors sIL-2R, Tumor necrosis factor receptor 1 (sTNF-R1) and sTNF-R2, chemokines CCL2, CCL3, CCL4, CCL20, CCL28, CDCP1, CXCL9 and CXCL10, and soluble markers sCD40L, plasminogen activator inhibitor 1 (PAI-1), pentraxin-3 (PTX3), myeloperoxidase (MPO), monocyte chemoattractant protein (MCP)-1, MCP-2, macrophage-inflammatory protein (MIP)-1α and MIP-1β6,14,40,43,45,46.