Platelet function in anaphylaxis.

Human platelets, following immunological or nonimmunological activation, are capable of releasing a variety of biologically active mediators and are able to actively participate in hypersensitivity reactions, including anaphylaxis. These cells constitutively express functional receptors for the Fc fragment of IgE, both the low affinity receptor (Fc epsilonRII) and the high affinity receptor (Fc epsilonRI), and could be activated via IgE. Alterations in platelet function have been demonstrated in patients with allergy and nonallergic hypersensitivity, including hypersensitivity to acetylsalicylic acid. Moreover, activated platelets may be responsible for anaphylactic transfusion reactions. Various haemostatic disturbances, particularly a drop in platelet number, were observed during anaphylactic shock. The current review summarises the data from human and experimental studies on platelet function in anaphylactic reactions.