[³H]-thymidine incorporation in sorted, highly purified αβ- and γδ-T cells: late, but not early, enhanced γδ–T-cell proliferation induced by mAb S5.2.

Protected PBMC cultures were initiated as described with all cultures receiving IFN-γ, IL-12, and mAb S5.2 on day 0 and OKT3 and IL-2 on day 1. (A) Early time points. After 24 hours (day 2), αβ- and γδ-T cells were sorted to high purity using FACS (greater than 98% pure and greater than 96% viable; not shown). Then they were plated at equivalent densities (5000 cells/well) in 96-well microtiter trays and were either stimulated with IL-2 at 100 U/mL or left unstimulated (PBS; indicated as no IL-2). After an additional 24 hours, [³H]-thymidine was added to cultures; 18 hours later, cells were harvested onto glass fiber filters. (B) Late time points. As above, but after 3 weeks, αβ- and γδ-T cells were sorted to high purity from cultures initiated in parallel; these cells were then assessed for proliferative capacity as described. Data are presented as mean cpm (± SD) of triplicate determinations. Results are representative of experiments performed using materials obtained from at least 2 different persons.