Figure 2.

VISTA prevents the release of granzyme B from human T cells into acute myeloid leukemia (AML) cells. THP-1 human AML cells and Jurkat T cells were pre-treated 24 h with 100 nM phorbol 12-myristate 13-acetate (PMA). Medium was changed and the cells were co-cultured at a ratio of 1:1 for 16 h in the absence or presence of VISTA-neutralizing antibody or isotype control antibody (A). Levels of secreted galectin-9 were measured by enzyme-linked immunosorbent assays (ELISA) (B). Granzyme B activity was measured in both THP-1 and Jurkat T cells as outlined in Materials in Methods (C). Data are shown as mean values ± SEM of four independent experiments; *p < 0.05, **p < 0.01 vs control or indicated events.