Figure 7.

The phosphatase activity of PP2A is required for CTLA-4-mediated T cell activation. Stably transfected Jurkat T cells were cultured overnight in the presence of doxycycline (1 μg/ml) to induce the expression of WT CTLA-4 or CTLA-4 mutant molecules. The cells were further cultured in the presence of doxycycline and stimulated with 24:26 (100 μg/ml) in the presence or absence of OA (0.01 μM) for 48 hours at 37°C. Supernatants were harvested and IL-2 production was measured by ELISA. For each CTLA-4 variant the percent of IL-2 produced in the presence of OA was normalized to IL-2 levels in the absence of OA. All graphs are representative of at least two independent experiments.