 Interleukin-6 inhibition might limit infarct size through reduced myocardial inflammation, but theoretically, it could also inhibit the repair process within the injured area. While the recent study suggests that IL-6 inhibition has largely favourable effects in NSTEMI, it remains to be seen if similar, beneficial effects can be obtained in patients with STEMI. On this background, the investigators want to investigate the effect of tocilizumab in patients with acute STEMI. The postulate is that a single dose of tocilizumab RoActemra will have favourable effects on infarct size, as assessed by markers of myocardial necrosis and cardiac magnetic resonance imaging CMR, without negative consequences for the repair process in these patients. The hypothesis will be tested in a randomised, double blind, placebo controlled trial comprising 200 patients with acute STEMI. 