Invariant natural killer T cells and incidence of first-time coronary events: a nested case-control study

AIMS: Invariant natural killer T (iNKT) cells, a T cell subset that is CD1d-restricted and expresses a semi-invariant T cell receptor, have been proposed to contribute to dyslipidaemia-driven cardiovascular disease due to their ability to specifically recognize lipid antigens. Studies in mice have attributed pro-atherogenic properties to iNKT cells, but studies in humans investigating associations of iNKT cells with incident coronary events (CE) are lacking. METHODS AND RESULTS: Here, we used flow cytometry to enumerate circulating iNKT cells (CD3(+) CD1d-PBS57-Tetramer(+)) in a case-control cohort nested within the prospective population-based Malmö Diet and Cancer Study (n = 416) to explore associations with incident first-time CE during a median follow-up of 14 years. We found a significant inverse association between CD4(−) and CD8(−) double negative (DN) iNKT cells and incident CE, with an odds ratio of 0.62 [95% confidence interval (CI) 0.38–0.99; P = 0.046] comparing the highest vs. the lowest tertile of DN iNKT cells. The association remained significant after adjustment for cardiovascular risk factors with an odds ratio of 0.57 (95% CI 0.33–0.99; P = 0.046). In contrast, total iNKT cells were not significantly associated with incident CE after adjustment, with an odds ratio of 0.74 (95% CI 0.43–1.27; P = 0.276). CONCLUSION: Our findings indicate that animal studies suggesting an atherosclerosis-promoting role for iNKT cells may not translate to human cardiovascular disease as our data show an association between high circulating numbers of DN iNKT cells and decreased risk of incident CE.