Platelets and innate immunity.
Although platelets are best known as primary mediators of hemostasis, this function intimately associates them with inflammatory processes, and it has been increasingly recognized that platelets play an active role in both innate and adaptive immunity. For example, platelet adhesive interactions with leukocytes and endothelial cells via P-selectin can lead to several pro-inflammatory events, including leukocyte rolling and activation, production of cytokine cascades, and recruitment of the leukocytes to sites of tissue damage. Superimposed on this, platelets express immunologically-related molecules such as CD40L and Toll-like receptors that have been shown to functionally modulate innate immunity. Furthermore, platelets themselves can interact with microorganisms, and several viruses have been shown to cross-react immunologically with platelet antigens. This review discusses the central role that platelets play in inflammation, linking them with varied pathological conditions, such as atherosclerosis, sepsis, and immune thrombocytopenic purpura, and suggests that platelets also act as primary mediators of our innate defences.
Semple
John W
JW
Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada. semplej@smh.toronto.on.ca
Freedman
John
J
D055371:Acute Lung Injury / Q000276:immunology; D056704:Adaptive Immunity; D050197:Atherosclerosis / Q000276:immunology; D001792:Blood Platelets / Q000276:immunology*; D006801:Humans; D007113:Immunity, Innate; D007249:Inflammation / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D009504:Neutrophils / Q000276:immunology; D017713:Platelet Transfusion / Q000009:adverse effects; D011971:Receptors, Immunologic / Q000378:metabolism; D018805:Sepsis / Q000276:immunology; D051193:Toll-Like Receptors / Q000378:metabolism; D000073871:Triggering Receptor Expressed on Myeloid Cells-1
D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; C408842:TREM1 protein, human; D051193:Toll-Like Receptors; D000073871:Triggering Receptor Expressed on Myeloid Cells-1