pDC expression and secretion of GrB depend on JAK activation, endosomal acidification, and active intracellular transport. pDCs were activated for 16 hours in the presence of IL-3 and IL-10 and various inhibitors. All inhibitors were nontoxic for pDC at the concentrations used. GrB expression in pDCs was analyzed by FACS. (A) Line graphs show GrB expression with and without various inhibitors as measured by intracellular staining for GrB from 4 individual experiments. (B) Zebra plots show GrB expression in pDCs from one representative experiment. (C) GrB secretion by purified pDCs was detected using a specific ELISPOT. Shown are results from 2 representative donors of 4.