IL-18BP displays a high affinity for IL-18 (Kd 399 pM) (Kim et al., 2000) and is present in the serum of healthy subjects at 20-fold molar excess to IL-18 to blunt the TH1 response to foreign organisms and reduce autoimmune responses to routine infection (Dinarello et al., 2013). Here, IL18 is linked to infection.