High prevalence of circulating CD4+CD28- T-cells in patients with small abdominal aortic aneurysms

Objective-To assess the possible role of proinflammatory CD28(-) T cells in abdominal aortic aneurysms (AAAs). Animal studies and human tissue studies suggest a role for interferon (IFN)-gamma-producing T cells in the development and progression of AAAs. Methods and Results-Fluorescence-activated cells sorter analysis of peripheral blood samples and measurement of AAA size using sonography were performed in 101 AAA patients and 38 healthy controls. Peripheral percentages of CD28(-) T cells of the CD3(+)CD4(+) and the CD3(+)CD8(+) were enriched in AAA patients with 7.8 +/- 8.8% and 41.9 +/- 15.7% compared with healthy controls with 2.2 +/- 6.1% and 24.9 +/- 15.5%, respectively (P=0.002 and P<0.001, respectively). Both CD4(+)CD28(-) and CD8(+)CD28(-) T cells produced large amounts of IFN-gamma and perforin. Patients with small AAAs (<4 cm) showed higher peripheral levels of CD4(+)CD28(-) T cells than those with larger AAAs (P=0.025). Immunohistological examinations revealed 39.1 +/- 17.2% CD4(+)CD28(-) and 44.0 +/- 13.8% CD8(+)CD28(-) in AAA tissue specimens with inflammatory infiltrates. Conclusions-IFN-gamma- and perforin-producing CD28(-) T cells are present in the periphery and the vessel wall of a majority of AAAs. This observation in humans favors the concept of a T cell-mediated pathophysiology of AAAs, especially during the early development of AAAs.