Association between CD8+ T-cell subsets and cardiovascular disease.

BACKGROUND: The findings of experimental studies suggest that the immune system plays a key role in atherosclerosis, but the clinical importance of different immune cells in cardiovascular disease remains poorly characterized. In this study we investigated the association between CD8(+) T cells and carotid disease as well as development of cardiovascular disease events.
METHODS: The study cohort comprised 700 subjects from the cardiovascular arm of the Malmö Diet and Cancer Study. Peripheral blood mononuclear cells, obtained at the 1991-1994 baseline investigation and stored at -140 °C, were thawed and the different CD8(+) T-cell populations analysed by flow cytometry. Baseline carotid intima-media thickness and stenosis were assessed by ultrasonography and clinical events were monitored through validated national registers.
RESULTS: Subjects with a high fraction of CD8(+) T cells were characterized by decreased cytokine release from activated leucocytes, metabolic signs of insulin resistance and increased incidence of coronary events; hazard ratios (95% confidence intervals) for the second and third tertiles of CD8(+) T cells were 2.57 (1.16, 5.67) and 2.61 (1.19, 5,71), respectively, in a Cox proportional hazards regression model. Correlations were found between the fraction of CD8(+) CD25(+) T cells and the degree of carotid stenosis (r = 0.11, P < 0.01), and between the CD8(+) CD56(-) IFN-γ(+) T-cell fraction and the degree of stenosis (r = -0.18, P < 0.005). The association between CD8(+) CD56(-) IFN-γ(+) T cells and carotid stenosis remained significant after controlling for major cardiovascular disease risk factors.
CONCLUSION: This study provides prospective clinical evidence for a role of CD8(+) T cells in cardiovascular disease and suggests the existence of CD8(+) T-cell subsets with different pathological functions.