PREDICTION OF MYOCARDIAL-INFARCTION IN DYSLIPIDEMIC MEN BY ELEVATED LEVELS OF IMMUNOGLOBULIN CLASS-A, CLASS-E, AND CLASS-G, BUT NOT CLASS-M

Background: Immune mechanisms have been suggested to play an important role in the development of coronary atherosclerosis and its thromboti c complications. We evaluated the predictive value of the levels of va rious serum immunoglobulin classes in middle-aged men at increased ris k of myocardial infarction. Methods: Using nested case-control design and logistic regression analysis, we estimated the association between serum immunoglobulins and the risk of coronary end points (nonfatal o r fatal myocardial infarction or sudden cardiac death) in dyslipidemic men (levels of non-high-density lipoprotein cholesterol >5.2 mmol/L [ >201 mg/dL]) participating in the Helsinki Heart Study. The cases cons isted of 135 subjects in whom a coronary end point occurred during the 5-year observation period of the study, and the controls,were 135 sub jects who did not suffer coronary end points during this period. Level s of IgA, IgE, IgG, and IgM were determined in serum samples collected at study entry. Results: Levels of IgA, IgE, and IgG, but not IgM, we re significantly higher in cases than in controls. After adjustment fo r other risk factors, such as age, smoking, and blood pressure, the ri sk of coronary disease showed a significant relation to the levels of IgA, IgE, and IgG. The risk in the highest quartile of each distributi on as compared with the lowest quartile was 2.2-fold for IgA (95% conf idence interval, 1.0-4.5), 2.8-fold for IgE (1.3-5.9), and 2.8-fold fo r IgG (1.3-5.9). Hypertriglyceridemia and a low level of high-density lipoprotein cholesterol were associated with increased risk of a coron ary end point only if the levels of IgA, IgE, or IgG were also elevate d. Conclusion: Elevated levels of IgA, IgE, and IgG are associated wit h myocardial infarction and cardiac death in men with dyslipidemia. Th e present data suggest that, for dyslipidemia to cause coronary athero thrombosis, an immune response reflected by elevated levels of these i mmunoglobulin classes is an important determinant.