Platelet activation during allergic inflammation

Blood platelets, apart from their traditional and well-recognised function in haemostasis, play an essential and active role in allergic inflammation e.g. through their participation in cell recruitment from blood to site of immune reactivity as a result of direct interactions with leukocytes, and through the release of inflammatory mediators. Platelet activation may occur during human allergic reactions both systemically and locally at the site of allergic inflammation as a result of an IgE-dependent process and as a secondary event caused by other inflammatory or immune stimuli. Altered platelet function as measured by platelet secretion, expression of surface molecules, aggregation, adhesion or arachidonic acid metabolism has been found in patients suffering from allergic diseases. These blood elements have been implicated in the pathogenesis of allergic diseases associated with the so-called atopic diathesis. This paper reviews the platelet activity and reactivity in allergic inflammation, along with our own findings concerning platelet release reaction and the phenomenon of platelet aggregation in patients with different clinical forms of allergy.