Platelets are the second most abundant cell in the circulation with >1 trillion patrolling the vasculature at any one time. Therefore, in addition to their well-appreciated role in mediating hemostasis, they serve important immune functions.61,62 Platelets are equipped with a number of receptors and granular proteins affording them important roles in the immune response. Indeed, activated platelets release a number of chemokines from their alpha and dense granules that facilitate leukocyte recruitment to sites of vascular injury/inflammation. These include CXCL1, PF-4 (platelet factor 4/CXCL4), CXCL5, NAP-2 (CXCL7), and CCL3, RANTES (regulated on activation, normal T-cell expressed and secreted) (CCL5), and CCL7.63 The release of these chemokines by platelets enhances leukocyte recruitment and adhesion to platelet thrombi and also serves to modulate leukocyte functional responses. Moreover, while lacking a nucleus, platelets express IL-1β mRNA that can be translated and secreted as mature IL-1β by activated platelets.64 Further supporting the recruitment of leukocytes, platelets express a range of receptors that facilitate leukocyte adhesion. Activated platelets express P-selectin which allows leukocyte tethering via leukocyte expressed PSGL-1 (P-selectin glycoprotein ligand 1), while GP-Ib facilitates stable adhesion via binding to the leukocyte integrin Mac-1.65,66 More recently, platelets have been observed to have the unique ability to migrate, scavenge, and bundle bacteria up, thereby presenting them to neutrophils for phagocytosis and triggering the release of neutrophil extracellular traps (NETs), which can be induced by the P-selectin/PSGL-1 interaction as well as the recently described platelet GPIIb/IIIa (αIIbβ3, CD41/CD61) interaction with SLC44A2 (CTL-2) on neutrophils.67–69 Activated platelets further support coagulation by the release of inorganic polyphosphate (PolyP) from platelet dense granules which drives intravascular thrombin formation due to its ability to activate FXII.70 Last, activated platelets release microvesicles, small particles ranging in size from 100 to 1000 nm, that are enriched in lipid and can carry a range of cargo including cytokines and chemokines, such as IL-1β, CXCL4, CXCL7, and CCL5, growth factors, microRNA, and mitochondria.71 Moreover, CRP has recently been demonstrated to bind platelet microvesicles and activate complement via binding C1q.72 Thus, the release of platelet microvesicles can regulate immune responses by mediating a range of target cells, particularly leukocytes and endothelial cells.