Schematic of the experimental procedure. (1) Double emulsion droplets (DEDs) are collected, conjugated first with streptavidin, and then with MHC-antigen complex and surface ligands for T cell activation. The functionalized DEDs are named aAPC-shells. The aAPC-shells are converted into aAPC-BLMs in 1X PBS or are broken into oil drops in 2X PBS + 50% Glycerol. aAPC-shells, oil drops, and other control groups are used to compare with aAPC-BLMs. (2) aAPC-BLMs are incubated with PBMC for 5 days. During the incubation, aAPC-BLMs interact with the T cells in PBMC and activate them. (3) The number of NYESO+ CD8 and CD4 T cells are quantified by flow cytometry and the cytokines (TNFα, IFNγ, IL-10, and IL-2) secreted by the cells are analyzed by ELISA.