Increase of chlamydial LPS antibodies in patients with acute coronary syndrome without detection of chlamydial DNA in atherectomy samples.

BACKGROUND: Chlamydia pneumoniae, a respiratory pathogen, has been connected with the pathogenesis of coronary artery disease (CAD). Previous studies indicated a correlation between antibodies to chlamydial LPS and the risk of cardiovascular disease. The aim of this study was to determine whether C. pneumoniae plays a direct role in the pathology of acute coronary syndromes (ACS). METHODS AND RESULTS: Twenty-five consecutive patients (median age 56 years) with ACS (17 acute myocardial infarction, 8 unstable angina) were included in the study and underwent directional coronary atherectomy. Tissue and blood samples were subjected to conventional and real time polymerase chain reaction (PCR) for C. pneumoniae. Antichlamydial immunoglobulin A (IgA) and IgG were examined by LPS enzyme immunoassay (EIA) and microimmunofluorescence (MIF) at intervention and on days 20, 45 and 180 thereafter. DNA of C. pneumoniae was detected neither in atherectomy samples nor in peripheral blood. Serologic results with LPS EIA showed a rapid and significant increase in specific IgA and IgG within 20 days including seroconversion in six cases (4 IgA, 2 IgG). Positive IgA and IgG MIF levels (30% and 87%) remained stable throughout the observation period. CONCLUSIONS: We conclude that negative detection of chlamydial DNA excludes a direct role of chlamydia in ACS. Our findings of rapid LPS antibody increase suggest a role of chlamydial LPS antigen which appears to be released during the acute event e.g. from damaged tissue, indicating a renewed accessibility to the immune system. An indirect role of chlamydia in the further aetiologic process of CAD seems possible.