The blood platelet as an inflammatory cell.

Platelets seem to be involved in inflammatory responses. They release substances which can cause vasodilation or vasoconstriction. Platelet Derived Growth Factor (PDGF) induces monocyte accumulation and activation and there is evidence that some mediators released from these cells can affect neutrophil migration as well as function. Furthermore, platelet derived cytokines participate in the processes of tissue repair, particularly fibroblast proliferation and matrix remodelling. We review some of the possible mechanisms which have been proposed to explain this role of platelets in the appearance and persistence of inflammatory reactions at the tissue sites.