Genetic disruption of CD8+ T cell function in this study resulted in an increase in atherosclerosis in Apoe−/− mice, associated with a decrease in CD8+ regulatory T cells, an expansion of T follicular helper and germinal center B cells (GC B cells), increased levels of plasma immunoglobulin levels, and the formation of adventitial ectopic germinal centers in atherothrombotic arteries. Here, CD8A is linked to atherosclerosis.