Loss of natural killer cell activity in patients with coronary artery disease

Background Natural killer (NK) cells are important components of the innate immune system and have a potential role in the regulation of autoimmunity. In the present study, we evaluated the NK cells in patients with coronary artery disease (CAD) and related the findings to clinical and laboratory parameters of the disease. Methods and results We studied 45 patients with acute coronary syndrome (ACS), 50 patients with stable angina and angiographically verified CAD (SA) and 50 healthy controls. The distribution of NK cell subsets was determined by flow cytometry and NK cell-mediated cytotoxicity was quantified ex vivo. Both ACS and SA patients had significantly reduced numbers of CD56dim NK cells compared with controls. The patients also exhibited a significant decrease in NK cell activity. The loss in NK cell function was not related to inflammatory activity or metabolic status. Conclusion Both stable and unstable conditions of CAD were associated with a redistribution of circulating lymphocytes, comprising a significant reduction of CD56dim NK cells and a concomitant loss of NK cell function. The findings suggest the presence of a persistent immune aberration in CAD patients independent of their clinical setting or systemic inflammatory state.