Serologic response against cardiolipin and enterobacterial common antigen in young patients with acute myocardial infarction.

Elevation of anticardiolipin antibodies has been observed in myocardial infarction and in many infections. To elucidate this topic, paired serum specimens from 40 patients with acute myocardial infarction were tested for anticardiolipin antibodies (solid-phase enzyme immunoassay) and enterobacterial common antigen antibodies (indirect hemagglutination test). Forty-one randomly selected individuals and 30 patients with chronic coronary heart disease served as controls. All individuals were males whose maximum age was 50 years. In patients with acute myocardial infarction the levels of anticardiolipin antibodies in paired sera rose significantly in all immunoglobulin classes (18% in the IgG class, 26% in the IgA class, and 43% in the IgM class), whereas no elevations occurred in the other groups. Fifteen of the acute myocardial infarction patients also showed at least a fourfold increase in enterobacterial common antigen antibodies, as compared with only one such increase in the two other groups combined. The increases were less marked than those seen in pronounced enterobacterial infections. These two reactions were closely associated.