[Tryptase levels are elevated during spontaneous ischemic episodes in unstable angina but not after the ergonovine test in variant angina].
Activated mast cells are present in human coronary atheromas, as well as in the adventitia of patients with variant angina, and may play an important role in plaque rupture and coronary vasomotion. To assess whether or not activation of mast cells is a primary event, we measured serum levels of tryptase, a specific marker of mast cell activation, in 8 patients with unstable angina during a spontaneous ischemic episode (Group 1) and in 5 patients with variant angina (Group 2) during ergonovine-induced coronary spasm. Blood samples were collected as soon as possible after the onset of pain and ECG changes (0 min), and after 5, 15 and 60 min. Tryptase levels in Group 1 were 0.13 U/l (range 0.017-0.44) at the onset of pain and significantly raised to 0.75 U/l (range 0.05-2.49) at 5 min, decreasing to 0.076 U/l (range 0.018-0.16) at 15 min and to 0.085 U/l (range 0.01-0.25) at 60 min (p = 0.035). Conversely, tryptase levels in Group 2 were 0.09 U/l (range 0.07-0.13) at 0 min, 0.11 U/l (range 0.07-0.22) at 5 min, 0.10 U/l (range 0.07-0.18) at 15 min, 0.11 U/l (range 0.07-0.17) at 60 min (NS). In conclusion, tryptase levels raise during spontaneous ischemic episodes in unstable angina, but not after ergonovine-provoked ischemia in variant angina, suggesting that a primary, yet unknown stimulus, may activate mast cells during some ischemic episodes in unstable angina.