Distribution of Chlamydia pneumoniae in the human arterial system and its relation to the local amount of atherosclerosis within the individual

Background-Chlamydia pneumoniae has been suggested to play a role in the or igin of atherosclerosis. We studied the prevalence of C pneumoniae at multi ple locations in the arterial system within the same individual. Studying t he association between atherosclerosis and C pneumoniae within the individu al excludes confounding by interindividual variability. Methods and Results-Postmortem, the presence in the intima/plaque and media of C pneumoniae membrane protein was determined by use of a C pneumoniae-s pecific monoclonal antibody. In 24 individuals, 33 arterial locations were studied (n = 738 segments). Area stenosis was determined in adjacent cross sections. In all individuals, immunostaining of C pneumoniae was observed i n greater than or equal to1 artery. The highest prevalences were observed i n the abdominal aorta (67%), internal and common iliac arteries (41%), and coronary arteries (33%). The lowest prevalences were observed in the radial (0%) and cerebral (2%) arteries. Within the individual, area stenosis was larger in cross sections with immunoreactivity compared with cross sections without immunoreactivity (31.0 +/- 11.9% versus 14.3 +/-6.1%, respectively ; P<0.001). In the individual, immunoreactivity was observed in 15<plus/min us>10% of the arteries (range, 3% to 45%). Between individuals, the percent age of arteries with immunoreactivity to C pneumoniae was associated with t he average area stenosis throughout the arterial system (r(2)=0.56, P<0.001 ). Conclusions-C pneumonine was mostly observed at locations that are related to clinically relevant features. Within the individual, the distribution of C pneumoniae is associated with the distribution of atherosclerosis. The r ole of the microorganism in atherosclerotic disease remains to be elucidate d.