CD8 T-cell function. CD27 deficiency compromises effector function and survival of CD8⁺ T cells. (A-B) PBMCs were stained with mAbs to CD8, CCR7, CD45RA, granzyme B, and perforin. Expression levels of (A) granzyme B or (B) by CD8⁺ T_CM, T_EM, and T_EMRA cells were determined relative to naive CD8⁺ T cells (normalized to 1.0). (C) PBMCs from healthy individuals (n = 5) and CD27-deficient individuals (n = 5) were stimulated for 14 hours (PMA/ionomycin) in the presence of brefeldin A and monensin. Percentage of cells expressing IFNγ, TNF, IL-2, or CD107a was determined by intracellular staining and flow cytometric analysis. (D-E) CD8⁺ memory (T_CM/T_EM; D) and T_EMRA (E) cells were sort-purified from healthy individuals (n = 6) and CD27-deficient individuals (n = 4) and cultured with anti-CD2/CD3/CD28 mAbs for 5 days. Proportions of cells expressing IFNγ, CD107a, or perforin were determined by intracellular staining and flow cytometry; secretion of IFNγ, TNFα, IL-2, and granzyme A and B was determined by cytometric bead arrays. (F-G) PHA blasts were expanded from PBMCs from healthy donors (n = 5) and CD27-deficient patients (n = 3). After 5 to 7 days, the cells were restimulated with plate-bound α-CD3. (F) Percentage of apoptotic cells was determined after 24 hours. (G) Relative expression of FASLG expression was determined after 4 hours stimulation with α-CD3 mAb (normalized to PHA blasts from healthy donors). For all graphs, values represent mean plus or minus SEM. Statistics performed using Student t tests with Mann-Whitney tests. *P < .05; ** P < .01.