CD8⁺ T cells from CLL patients show increased production of IFNγ and TNFα, and increased expression of TBET, but normal production of IL2. Cytokine production by CD8⁺ T cells was assessed by intracytoplasmic staining for IFNγ, TNFα, and IL2 after stimulation with PMA and ionomycin. CD8⁺ T cells from CLL patients showed increased production of IFNγ (A) and TNFα (B) reflecting the global skew toward CD8⁺CCR7⁻ subsets (T_EM and T_EMRA). (C) In contrast, there was no significant difference in the production of IL2 by CD8⁺ T cells from patients and controls. (D) CD160 was expressed on CD8⁺ T cells that produced IFNγ but not on cells producing IL4, consistent with its expression being restricted to Tc1 cells. (E) The expression of TBET in CD8⁺ T-cell subsets from CLL patients was analyzed as defined by coexpression of CCR7 and CD45RA as before. The expression of TBET was increased in T_EM cells, with the highest expression levels in the T_EMRA subset. (F) CD3⁺CD8⁺CCR7⁻ T cells from patients with CLL show significantly increased TBET expression compared with controls.