Unstable atherosclerotic plaques contain T-cells that respond to Chlamydia pneumoniae

Objective: Atherosclerotic lesions are characterized by an immune mediated chronic inflammation. Seroepidemiological studies support a relationship between atherosclerotic disease and infection with C. pneumoniae; an association further endorsed by immunocytochemical and DNA directed studies. However, the question arises whether C. pneumoniae acts as a causal antigen, or is merely a bystander. For this reason we have analyzed the T lymphocyte population of carotid atherosclerotic plaques of symptomatic patients for their response against C. pneumoniae. Methods: T cell lines were generated from carotid endarterectomy tissues obtained from eight patients with symptomatic disease. The response of these T cell lines against C. pneumoniae elementary bodies was analyzed by H-3-thymidine incorporation. T cell clones were generated by limiting dilution from the cell lines of three patients and tested for antigen specificity in the same manner. Furthermore, cytokine profiles (Thl/Th0/Th2) were established by measuring the production of IFN-gamma and IL-4. Results: Of the eight T-cell lines five responded to C, pneumoniae. Eighteen of 69 CD4-positive clones, generated from three patients with a positive T cell Lines response, responded to C. pneumoniae also. The majority (17/18, 96%) of these clones showed a Th1 cytokine profile. Conclusion: These results show that in a subpopulation of symptomatic patients C. pneumoniae can activate T cells within atherosclerotic plaques suggesting that a C. pneumoniae enhanced proinflammatory Th1 response contributes to plaque destabilization in these patients. (C) 2000 Elsevier Science B.V. All rights reserved.