Detection of Chlamydia pneumoniae in peripheral blood mononuclear cells:: correlation with inflammation and atherosclerosis in haemodialysis patients

Background. Chlamydia pneumoniae has been implicated as an inflammatory agent in atherosclerosis. Clinical studies in this field have yielded conflicting results, which may have resulted from a lack of standardization for C. pneumoniae detection. We attempted to accurately estimate C. pneumoniae prevalence and to examine whether C. pneumoniae is associated with atherosclerosis and inflammation in haemodialysis (HD) patients. To do this, we assessed C. pneumoniae presence by a combination of methods and correlated its levels with inflammatory and atherosclerotic indexes in these patients. Methods. Chlamydia pneumoniae was identified by polymerase chain reaction (PCR) in DNA extracted from cell cultures inoculated with patient buffy coats and by serum IgG antibodies against C. pneumoniae (IgGCp). Inflammation was assessed by C-reactive protein and serum amyloid A and atherosclerosis was evaluated from clinical and laboratory data. Results. Of the 130 patients, only nine had viable C. pneumoniae in peripheral blood mononuclear cells (PBMCs) while 64 had serum IgGCp. Although patients with viable C. pneumoniae had higher atherosclerotic scores, seropositive and negative patients showed similar scores. Patients with atherosclerosis exhibited higher inflammatory indexes. Neither patients with detectable C. pneumoniae in PBMCs nor seropositive subjects had higher inflammation than negative patients. Conclusions. We found that viable C. pneumoniae in PBMCs, assessed by cell culture and PCR, was present in a small percentage of HD patients and was correlated with atherosclerosis. Seropositivity was much higher in HD patients but was not associated with viable C. pneumoniae or with atherosclerosis. Further studies in HD patients using high sensitivity and specificity methods in larger populations will be necessary to clarify the relationship between C. pneumoniae and atherosclerosis.