CD40LG and Sepsis: The P-Selectin–PSGL-1 interaction acts as a key checkpoint in the maturation of monocytes into DCs.99 Activated platelets also express CD40L, an important stimulator of DC function which is required for an effective adaptive immune response.100,101 Kupffer cells, the resident macrophages of the liver, “capture” circulating platelets in liver sinusoids and use them to encase bacteria using the GPIb–CD11b interaction.102 This contributes to the propensity for clot formation in the liver in the context of sepsis.