Serum tryptase levels in acute coronary syndromes

Background Mast cell accumulation and activation have been demonstrated in the vulnerable shoulder regions of atherosclerotic plaques and at the actual sites of plaque erosion and rupture. When activated and degranulated, mast cells release tryptase, a neutral protease, capable of activating matrix metalloproteinases and predisposing to plaque rupture. We tested the hypothesis that in acute coronary syndromes the levels of serum tryptase would reflect mast cell activation. Methods and results The study population consisted of 183 patients admitted to the emergency room of 3 general hospitals because of acute chest pain of ischemic origin. Of these patients, 64 suffered from exertional angina presenting with acute chest pain, 60 had unstable angina, and 59 had acute myocardial infarction. Serum tryptase levels were analyzed from samples drawn, on average at 7 h, and also at 24 h after the onset of the chest pain. As controls served 41 patients admitted for surgical treatment of inguinal hernia or varicose veins. Serum tryptase levels remained stable within the observation period, and no differences were detected between the patient groups and controls. On the other hand, the differences in C-reactive protein levels reflected the extent of myocardial injury. Conclusions In ACS, serum tryptase levels are normal and remain stable. Our results do not exclude the possibility of local activation of coronary mast cells, but suggest that the excess quantity of tryptase acutely released from mast cells in ACS, if any, is not sufficient to be detected by measuring tryptase concentration in the systemic circulation.