Notably, however, mean plasma levels of azurophilic granule components such as MPO in acute SCLS were nearly ninefold higher than those in septic plasma (514 vs 60 ng/mL).15 Similarly, although elevated levels of tertiary granule constituents including MMP9 are observed in sepsis and other systemic diseases with prominent vascular abnormalities such as Kawasaki syndrome, levels of MMP9 are twofold to fivefold higher in SCLS.16 Here, MPO is linked to capillary leak syndrome.