Unstable atherosclerotic plaques contain T-cells that respond to Chlamydiapneumoniae

Objective: Atherosclerotic lesions are characterized by an immune mediated chronic inflammation. Seroepidemiological studies support a relationship be tween atherosclerotic disease and infection with C. pneumoniae; an associat ion further endorsed by immunocytochemical and DNA directed studies. Howeve r, the question arises whether C. pneumoniae acts as a causal antigen, or i s merely a bystander. For this reason we have analyzed the T lymphocyte pop ulation of carotid atherosclerotic plaques of symptomatic patients for thei r response against C. pneumoniae. Methods: T cell lines were generated from carotid endarterectomy tissues obtained from eight patients with symptomat ic disease. The response of these T cell lines against C. pneumoniae elemen tary bodies was analyzed by H-3-thymidine incorporation. T cell clones were generated by limiting dilution from the cell lines of three patients and t ested for antigen specificity in the same manner. Furthermore, cytokine pro files (Thl/Th0/Th2) were established by measuring the production of IFN-gam ma and IL-4. Results: Of the eight T-cell lines five responded to C, pneumo niae. Eighteen of 69 CD4-positive clones, generated from three patients wit h a positive T cell Lines response, responded to C. pneumoniae also. The ma jority (17/18, 96%) of these clones showed a Th1 cytokine profile. Conclusi on: These results show that in a subpopulation of symptomatic patients C. p neumoniae can activate T cells within atherosclerotic plaques suggesting th at a C. pneumoniae enhanced proinflammatory Th1 response contributes to pla que destabilization in these patients. (C) 2000 Elsevier Science B.V. All r ights reserved.