Previous work has established that extracellular adenosine signaling is protective in mucosal inflammation and promotes the resolution of ongoing inflammation. The sources of extracellular adenosine include enzymatic processing from nucleotides, such as ATP, AMP, and diadenosine triphosphate (Ap3A), which can be liberated from a variety of cell types, including leukocytes. Here, we revealed that activated human neutrophils are a source of Ap3A, previously thought to be made primarily by platelets.