The proatherogenic properties of lipoprotein(a) may be enhanced through the formation of circulating immune complexes containing Chlamydia pneumoniae-specific IgG antibodies.

Abstract

To investigate a possible relationship between the atherogenic properties of lipoprotein(a) (Lp(a)) and Chlamydia pneumoniae infections. The study population was nested within the Västerbotten Intervention Program or the WHO MONICA project. In this incident case-control study, 78 patients who had suffered acute myocardial infarction and 156 matched controls were included. The contents of circulating immune complexes were analysed for C. pneumoniae IgG antibodies and Lp(a). A significantly larger proportion of cases than controls had >/=13 mg. l(-1)Lp(a) and a C. pneumoniae specific IgG antibody titre >/=1/2 in circulating immune complexes (odds ratio=3.8). The proatherogenic effects of Lp(a) may be enhanced and/or partly mediated through the formation of circulating immune complexes containing C. pneumoniae -specific IgG antibodies. The connection between chronic C. pneumoniae infections and atherosclerosis may, at least in part, be explained by an interaction with Lp(a) through the formation of circulating immune complexes.