IL1RN and COVID-19–associated multisystem inflammatory syndrome in children: Soluble receptors of tumor necrosis factor alpha (sTNF-R1 and sTNF-R2), CD40 ligand (sCD40L) and IL-2 (sCD25) were all higher in MIS-C patients as was interleukin-1 receptor antagonist (IL-1RA), a member of the IL1 family that binds the IL1-receptor to inhibit this pathway.