Both antigen and CD3 mAb effectively activate tumor-specific CTLs.

<p><b>A</b>. Activation markers CD69 and CD25 expression kinetics. CTLs were stimulated with either tumor cells or CD3 mAb for the indicated time points. Cells were stained with CD8-specific mAb plus CD69- or CD25-specific mAbs, respectively. The CD8-positive cells were gated and measured for CD69 and CD25 mean fluorescent intensity (MFI). <b>B</b>. Analysis of expression levels of effector molecules of the cytotoxic pathways. CTLs were stimulated with either irradiated tumor cells or CD3 mAb and harvested at the indicated time points. RT-PCR analysis was carried out using gene-specific PCR primers as indicated. LTβ is also used as a normalization control.