Impaired activation and reduced glucose uptake by CLL-derived CD8⁺ T cells upon stimulation. PBMCs from CLL patients and age-matched HDs were thawed and cultured for 2 (A-B,D-F) or 5 (C) days in the presence or absence of anti-CD3/CD28 antibodies. Cells were analyzed for (A) activation markers (CLL, n = 15-19; HD, n = 16-22), (B) degranulation (CLL, n = 12; HD, n = 12), (C) PD-1 expression (CLL, n = 8; HD, n = 8), (D) surface glucose transporter GLUT1 (measured by GLUT1 Ras-binding domain [RBD] green fluorescent protein [GFP] construct) (CLL, n = 6; HD, n = 4; data are the same as in supplemental Figure 1G), and (E) glucose uptake (2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose [2-NBDG]; CLL, n = 23; HD, n = 20; data are the same as in supplemental Figure 1F), and expression of (F) HIF-1α (CLL, n = 6; HD, n = 4). Normality was determined by a D’Agostino and Pearson normality test. The P value was calculated by an unpaired Student t test (A-C,E), or a Mann-Whitney test (A,D,F). Data are presented as mean plus or minus standard error of the mean (SEM). *P < .05; **P < .005; ****P < .0001.