Kovanen et al1 report an interesting prospective relationship between total IgA, IgG, and IgE levels and myocardial infarction in middle-aged dyslipidemic men with no evidence at baseline of coronary heart disease or any other major disease. The authors appropriately comment on these results, stating that subjects at risk are likely to have a complex immunologic activation, since it is not plausible that the rise in any single specific antibody may be reflected in a significant increase in total immunoglobulins. We have studied this subject with particular reference to serum IgA levels and have concluded that there is no independent prospective association between immunoglobulins and ischemic events.2,3 Indeed, IgA and IgG but not IgM levels tended to be associated with subsequent ischemic events in univariate analysis; however, IgA and IgG levels, again unlike IgM levels, also increased very significantly from the low to middle and high tertiles of C3 distribution.3 According to our data, serum C3 (the third complement component) is the most powerful independent predictor of myocardial infarction, at least in men.3 When our logistic regression model included C3 complement, no significant association between serum immunoglobulins and future ischemic events could be detected.
Muscari A, Puddu P. Immunoglobulins, C3, and the Risk of Myocardial Infarction. Arch Intern Med. 1999;159(19):2364-2365. doi: