Association of antibodies to chlamydial lipopolysaccharide with the endovascular presence of Chlamydophila pneumoniae in carotid artery disease

Atherosclerotic lesions often harbor Chlamydophila pneumoniae (C. pneumoniae). The objective of the present study was to examine whether serological tests are able to predict individual endovascular infection. Endarterectomy specimens from 70 patients with severe carotid artery stenosis were stained immunohistochemically for C. pneumoniae. Antibody titers to C. pneumoniae were measured in serum with a recombinant ELISA recognizing chlamydial lipopolysaccharide (cLPS) and with microimmunofluorescence (MIF). C. pneumoniae antigens were detected in 64 (91%) carotid artery specimens. Serum IgG antibodies to C. pneumoniae were detected in 43% of patients by cLPS-ELISA and in 77% by MIF test. Detection of C. pneumoniae positive cells within atherectomy specimens was strongly correlated to seroprevalence (P=0.002) and to titers (P=0.003) of cLPS-IgG antibodies, but not to results of the MIF-test. We conclude that cLPS-IgG antibodies hold promise as a surrogate marker to identify individuals with high endovascular antigen load.