Immune responses to Chlamydia antigens in atherosclerosis

Aim of this study was to isolate T lymphocytes from atheromatous plaques an d to determine they respond to Chlamydia antigens. Atheromatous plaques from carotid endarterectomy patients, were cultured in vitro with the T cell growth factor, IL-2. This rarely allowed outgrowth o f T cell lines. However, when combined with a mitogenic or antigenic stimul us to T cells, T cell lines were obtained from most patients, and from simi lar to 30% of replicate plague tissue fragments. Chlamydia organisms were a s effective in allowing the establishment of T cell lines as other recall a ntigens. T cell lines were tested for their ability to recognize antigens presented by autologous macrophages. Some lines responded to Chlamydia organisms, and also to the recombinant Chlamydia proteins hsp60 and OMP2. However, other lines recognized recall antigens. These results indicate that the atheromatous plague contains memory T lymph ocytes, and amongst the antigens they recognize are Chlamydia proteins. Sti mulation of T cells was required to allow outgrowth in vitro, suggesting th at the T cells were not in an activated state in vivo. However, since Chlam ydia pneumoniae is present in the atheromatous prague, activation of Chlamy dia-reactive T cells by local antigen is a potential pro-inflammatory mecha nism which could contribute to the pathogenesis of atherosclerosis.