Variations in lymphocyte activation during exercise testing in patients with coronary artery disease

Background: Several studies have shown that strenuous exercise induces changes in the immune system. Soluble interleukin-2 receptor (sIL-2R) is a marker of immune system activation and is known to increase in association with cardiac disease. The aim of the present study was to assess sIL-2R levels in patients with coronary artery disease (CAD) in conjunction with exercise testing. Methods: Blood levels of sIL-2R were determined in 10 healthy control individuals and 21 patients with CAD before exercising, at maximal exercise testing (Bruce) and at 0.5 h and 3-4 h after exercise (T1-T4). The study group had stable angina and normal or near-normal left ventricular function. Patients at risk of abnormal cytokine levels were excluded. Results: The patients were divided into two groups: those with mild to moderate ischemia (according to a thallium scan) (n = 14, group 1a) and those with severe exercise-induced ischemia (n=7, group 1b). The prevalence of anginal pain at exercise and mean ST depression were similar in both groups, however, signs of left ventricular dysfunction during exercise were significantly more frequent in group 1b. Mean sIL-2R levels (units per ml) showed no significant difference between group 1 a and the control group at all time points (503 ± 122, 518 ± 140, 489 ± 164, 461 ± 131 μ/ml compared with 505 ± 135, 509 ± 112, 469 ± 126, 416 ± 103 μ/ml, respectively, P = NS), while a significant increase in group 1b compared with the control group was found at 0.5-h after exercise (T3) (1147 ± 510 μ/ml, P = 0.03). Discussion: This study demonstrated immunological involvement in some patients with severe exercise-induced ischemia shortly after exercise, suggesting an association with heart failure.