Which of the following immune cells have the expression of CD8 on their faces

Ref Robbins 8/e p186-; 9/e p191 In this form of T cell-mediated tissue injury, CD8+ CTLs kill antigen-bearing target cells. As discussed earlier, class I MHC molecules bind to intracellular peptide antigens and present the peptides to CD8+ T lymphocytes, stimulat- ing the differentiation of these T cells into effector cells called CTLs. CTLs play a critical role in resistance to virus infections and some tumors. The principal mechanism of killing by CTLs is dependent on the perforin-granzyme system. Perforin and granzymes are stored in the granules of CTLs and are rapidly released when CTLs engage their targets (cells bearing the appropriate class I MHC-bound peptides). Perforin binds to the plasma membrane of the target cells and promotes the entry of granzymes, which are proteases that specifically cleave and thereby activate cellular caspases. These enzymes induce apoptotic death of the target cells (Chapter 1). CTLs play an impoant role in the rejection of solid-organ transplants and may contribute to many immunologic diseases, such as type 1 diabetes (in which insulin-producing b cells in pancreatic islets are destroyed by an autoimmune T cell reaction). CD8+ T cells may also secrete IFN-g and contribute to cytokine-mediated inflammation, but less so than CD4+ cells.