CD8 + T-Cell Subpopulations in Human Abdominal Aortic Aneurysm Lesion

Abstract

To the Editor: We read with interest the article by Duftner et al1 reporting the prevalence of peripheral interferon-γ (IFN-γ)–producing CD4+CD28− and CD8+CD28− T cells in patients with small abdominal aortic aneurysm (AAA). Along with the recent description that Th1-type immune responses predominate in human end-stage AAA lesion,2,3 their observation further supports preference toward polarized type 1 T-cell responses in aneurysm disease. The potential involvement of Th1 cells in the pathogenesis of the disorder is also suggested by the convincing demonstration that absence of CD4+ T cells or targeted deletion of IFN-γ prevents the induction of experimental AAA in a calcium chloride–induced mouse model,4 AAA formation being reconstituted by administration of IFN-γ into CD4−/− mice or infusion of competent splenocytes from wild-type mice into IFN-γ−/− mice. In their study, Duftner et al further established that both circulating CD4+CD28− and CD8+CD28− T cells are highly differentiated cells that display extensive CD45RO to CD45RA reversion and produce large amounts of IFN-γ and perforin. Surprisingly, low percentages of CD8+CD28− T cells were identified in AAA tissue sections using immunohistochemistry compared with flow cytometric analysis of peripheral blood mononuclear cells. In a series of our …