PLATELETS AND INFLAMMATION - ROLE OF PLATELET-DERIVED GROWTH-FACTOR, ADHESION MOLECULES AND HISTAMINE

Despite the fact that the relationship between platelets and the infla mmatory and immune responses has been reviewed previously, the allocat ion of platelets among the inflammatory cells is still at issue. Recen t developments in our understanding of platelet-associated signalling events have offered new potential insights into platelet functions in inflammatory and immune-related diseases. In recent years, it has been established that a range of molecules, mainly associated with the pla telet surface and/or the platelet granules, regulate the capacity of p latelets to cross-talk with other inflammatory cells during the proces s of inflammation, and of vascular inflammation in particular. This is the case with platelet-derived growth factor (PDGF), secreted from pl atelet alpha-granules, with P-selectin, expressed on the platelet surf ace, and with platelet histamine, which is secreted from platelets in response to aggregatory and inflammatory stimuli. The nature and mecha nism of action of these regulatory molecules, physiologically present in platelets and mobilised upon platelet activation and aggregation, i s the subject of this review. The participation of platelets, through PDGF, P-selectin and histamine, is also discussed in overtly inflammat ory disorders, such as acute respiratory distress syndrome, mesangial glomerulonephritis, chronic inflammatory bowel disease, disseminated i ntravascular inflammation, and allergic vasculitis, focusing on possib le pharmacological interventions specifically active against growth fa ctors, adhesion molecules and platelet histamine.