Fig. 3.

Knockdown of hTERT in naïve CD4 T cells increases apoptotic susceptibility and restricts clonal expansion during the priming response. CD4 T cells were purified from 5 normal donors by positive selection and transfected by nucleofection (AMAXA) with negative control or validated siRNA oligonucleotides specific for hTERT. Twenty-four hours later the transfected cells were stimulated with anti-CD3/CD28-coated beads. hTERT transcripts (A) and telomerase activity (B) were measured on day 3. The following parameters were determined on day 4: cell numbers (C), survival rates (D), apoptosis rates measured as PI-positive cells (E), TUNEL-positive cells (F), and lengths of telomeric sequences (G). Results are presented as means ± SEM.