Recent activation of the plaque immune response in coronary lesions underlying acute coronary syndromes

OBJECTIVE: To discriminate between chronic inflammation and acute activation of the plaque immune response in culprit lesions of patients with acute coronary syndromes. DESIGN: Retrospective study. SETTING: Tertiary referral centre. SUBJECTS: 71 patients having coronary atherectomy were classified according to their ischaemic syndrome: stable angina (n = 23); stabilised unstable angina (n = 18); refractory unstable angina (n = 11); and acute myocardial infarction (n = 19). MAIN OUTCOME MEASURES: Immunohistochemical measurement of interleukin 2 receptor (IL-2R) (CD25) positive cells expressed as a percentage of the total amount of (CD3 positive) T lymphocytes in frozen sections of atherectomy specimens. RESULTS: The number of lesions containing IL-2R (CD25) positive T cells increased with severity of the ischaemic coronary syndrome (stable angina, 52%; stabilised unstable angina, 77.8%; refractory unstable angina, 90.9%; acute myocardial infarction, 89.4%). The percentage of activated T cells (CD25/CD3 ratios x100) increased in lesions associated with refractory unstable angina (7.8%) and acute myocardial infarction (18.5%), compared with those in lesions associated with either chronic stable angina (2.2%) or stabilised unstable angina (3.3%). CONCLUSIONS: An increase in the percentage of IL-2R positive T lymphocytes in culprit lesions of patients with acute coronary syndromes indicates recent activation and amplification of the immune response within plaques. This may result in a burst of inflammatory products with tissue degrading and vasoactive properties and, hence, could initiate or accelerate the onset of an acute coronary event.