title: Increased CD8(+) T cells associated with Chlamydia pneumoniae in symptomatic carotid plaque.
abstract: OBJECTIVE
  The presence of Chlamydia pneumoniae has been reported in carotid atheroma, but its causative effect in the activation of an atherosclerotic plaque to a prothrombotic state remains unproved. Antigen- mediated activation of T lymphocytes within plaque may represent a mechanism by which infection can result in plaque conversion. The goal of the present study was to characterize the T-cell subtype profile related to the presence of C pneumoniae in patients with symptomatic versus asymptomatic carotid atherosclerosis.
  
  
  METHODS
  We studied 14 plaques (5 symptomatic and 9 asymptomatic) positive for C pneumoniae confirmed by polymerase chain reaction and 14 plaques (6 symptomatic and 8 asymptomatic) from age- and stenosis-matched patients negative for C pneumoniae by polymerase chain reaction. T-cell subpopulations of T-helper, T-cytotoxic, and T-memory lymphocytes were identified through indirect enzyme immunohistochemistry with anti-CD3+, anti-CD4+, anti-CD8+, and anti-CD45RO+ monoclonal antibodies, respectively. Results are expressed as the number of positive cells per millimeter squared.
  
  
  RESULTS
  In the absence of C pneumoniae, symptomatic plaques had a modest but significant increase of CD3+ (89.6 versus 55.3, P=0.013), CD4+ (57.3 versus 32.7, P=0.01), and CD45RO+ (82.8 versus 43.7, P=0.007), but not CD8+ T cells (28.5 versus 25.5, P=0.245) compared with asymptomatic. However, in the presence of C pneumoniae, there was significant increase of all T-lymphocyte subtypes in symptomatic plaques, including CD8+ (76.8 versus 30.3, P=0.03), CD3+ (192.1 versus 80.4, P=0.004), CD4+ (111.9 versus 37.9, P=0.003), and CD45RO+ (120.2 versus 72.9, P=0.003) cells compared with asymptomatic plaques. With use of 2-way ANOVA, both the presence of chlamydia and symptoms were associated with significantly higher T-cell counts (P<0.005 for all subtypes).
  
  
  CONCLUSIONS
  Although all patients with symptomatic disease show a modest elevation in the concentration of intraplaque lymphocytes, a preferential increase in CD8+ class I-restricted T cells is observed in symptomatic carotid plaque positive for C pneumoniae. These data provide incentive to further explore the role of Chlamydia in the modification of immune-mediated mechanisms in active atherosclerotic plaque.
authors.affiliation: Stroke Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Md, USA.
authors.forename: Z G
authors.initials: ZG
authors.lastname: Nadareishvili
authors.forename: D E
authors.initials: DE
authors.lastname: Koziol
authors.forename: B
authors.initials: B
authors.lastname: Szekely
authors.forename: C
authors.initials: C
authors.lastname: Ruetzler
authors.forename: R
authors.initials: R
authors.lastname: LaBiche
authors.forename: R
authors.initials: R
authors.lastname: McCarron
authors.forename: T J
authors.initials: TJ
authors.lastname: DeGraba
mesh_terms: D000368:Aged; D015703:Antigens, CD / Q000032:analysis / Q000096:biosynthesis; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D016893:Carotid Stenosis / Q000276:immunology / Q000382:microbiology* / Q000473:pathology*; D002452:Cell Count; D016993:Chlamydophila pneumoniae / Q000235:genetics / Q000302:isolation & purification*; D015331:Cohort Studies; D004269:DNA, Bacterial / Q000302:isolation & purification; D003710:Demography; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007156:Immunologic Memory / Q000276:immunology; D016130:Immunophenotyping; D020767:Intracranial Thrombosis / Q000209:etiology; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D016133:Polymerase Chain Reaction; D012307:Risk Factors; D016176:T-Lymphocyte Subsets / Q000145:classification / Q000276:immunology / Q000473:pathology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology / Q000378:metabolism / Q000473:pathology
chemical_list: D015703:Antigens, CD; D004269:DNA, Bacterial