Observational and trial data have accumulated to support the hypothesis that increased consumption of the longchain n-3 polyunsaturated fatty acids found in fish, especially eicosapentaenoic and docosahexaenoic acids, lower the risk of dying from coronary heart disease, 1 and interest has focused on the anti-arrhythmic properties of these fatty acids. In the late 1980s, McClennan et al2 were the first to show anti-arrhythmic properties associated with these fatty acids in animal models. Billman et al3 confirmed and expanded on these experiments in a dog model. Further experiments reported plausible cellular mechanisms for the anti-arrhythmic effects, including modulation of sodium, potassium, and calcium channels. 4 n-3 fatty acids might also have favourable actions on heart rate variability, and therefore could be exerting anti-arrhythmic actions through effects on the autonomic nervous system. 5 Burr et al6 published the first randomised trial of the effect of fish consumption on death from coronary heart disease, the Diet and Reinfarction Trial (DART). In DART, just over 2000 men with a history of myocardial infarction were randomised to three dietary strategies (lowering saturated fat, increasing fibre, and increasing fatty-fish intake). There was a 29% reduction in total mortality in the participants who received advice to eat at least two portions of fatty fish a week, but no difference in total events for coronary heart disease because more nonfatal myocardial infarctions occurred in the fish-advice group. To explain these apparently discordant effects on fatal versus non-fatal events, Burr et al suggested that fish consumption might reduce the risk of fatal arrhythmias, and therefore preferentially affect mortality after myocardial infarction. Siscovick et al7 addressed this hypothesis by studying whether dietary intake and blood levels of n-3 fatty acids were associated with risk of a primary cardiac arrest, in a retrospective population-based case-control design. In the US Physicians’ Health Study, 8, 9 we investigated the same questions with respect to sudden cardiac death in a prospective cohort of over 20000 apparently healthy US male physicians. Both studies showed relative-risk reductions of about 50% in risk associated with an intake of one fish-meal a week, and even more striking reductions of 81–90% in those with blood concentrations of n-3 fatty acid in the top quartile. We also studied non-fatal myocardial infarction and, similar to the DART trial, saw no benefit on this endpoint. 8, 10

B7-2, CD40, or CD40L, their expression of additional positive or negative costimulatory molecules of the expanding B7/CD28 or TNF/TNF-R families6 has not been systematically investigated. Allogeneic or autologous MSC could exert their immunoregulatory effects at sites of inflammation via provision of inhibitory costimulatory signals to antigen-reactive T cells, because such signals can be provided in cis or trans leading to T-cell inactivation. Alternatively, MSC might exert immunoregulatory effects and retain immunoprivilege in the inflammatory environment via secretion of soluble immunoregulatory mediators. Members of the transforming growth factor β superfamily, which are produced by MSC, can suppress T-cell-mediated antigen responses in vitro, 8, 9 and production of bone morphogenetic protein 2 by MSC might mediate immunosuppression via the generation of CD8+ regulatory cells. 10 Le Blanc and colleagues’ findings suggest that the immunomodulatory effects of MSC transplantation, irrespective of the mechanisms involved, are localised to and persist at the site of MSC engraftment, because the patient’s lymphocytes at 1 week and 1 month after the first MSC …