The Antiplatelet and Immune Response Trial

Platelets are the main type of blood cell involved in the formation of blood clots that cause heart attacks. The investigators give antiplatelet drugs (aspirin, for example) to reduce the risk of another clot forming in the future and causing another heart attack. Platelets are known to have a role in inflammation and infection as well as clotting. In a recent large clinical trial, known as the PLATO study, it was also shown that patients treated with a new antiplatelet medication (ticagrelor) developed fewer lung infections, as well as fewer heart attacks, compared to the current standard treatment (clopidogrel). The investigators would therefore like to investigate the reasons behind this and look at the effect of these medications on immune response. This may help us develop new drugs that have a better effect on immune response. The investigators are planning a clinical trial that investigates the effect of these medications on the immune response of healthy volunteers aged 18 to 65. Only volunteers with no significant past medical history and not taking any medications will be included. Thirty volunteers will receive either a normal dose of ticagrelor or clopidogrel or no antiplatelet medication for 1 week. They will then attend the Sheffield Clinical Research Facility where their immune response will be stimulated using a safe, well established method. The investigators will do this with an injection of a low dose of endotoxin, which is part of the surface coating of some bacteria and has been used extensively in similar studies, in over a thousand volunteers over the past 20 years to investigate immune response. It is known to cause temporary flu-like symptoms that last approximately 68 hours. The investigators will take measurements of inflammatory markers, white blood cell function and platelet function and compare the effect of ticagrelor and clopidogrel on this immune response.