Both CD2-mediated signals and IL-12 signaling contribute to the expansion of apoptosis-resistant γδ-T cells.

On day 0, separate PBMC cultures were initiated. Where indicated (+), IFN-γ (1000 U/mL), IL-12 (10 U/mL), or anti-CD2 mAb S5.2 (5 μg/mL) was added to cultures with PBS (−) added as a control. After 24 hours, all cultures received mitogenic stimulation with OKT3 and IL-2 (day 1). Cultures were maintained and expanded as described, and, after 21 days, γδ-T cells in each culture (first gated as CD3-APC⁺, TCR-γδ-PE⁺) were analyzed for apoptosis using 4-color FACS, as described above. The percentages of viable (annexin⁻/PI⁻) and apoptotic (annexin⁺/PI⁻) γδ-T cells in each dot plot are indicated in the corresponding quadrants. The absolute number of viable γδ-T cells (annexin⁻/PI⁻) found in each culture was determined with data expressed as the mean fold expansion of viable γδ-T cells (± SD), determined in triplicate. Results shown are representative of experiments performed using materials obtained from at least 3 different persons.