Inhibiting autophagy during interleukin-2 immunotherapy. Autophagic flux and diminished apoptosis are noted in established tumor cell lines, conferring resistance to chemotherapy, radiation therapy, and immunotherapy with interleukin 2. Chloroquine administration in vivo or, as shown here, in vitro can inhibit this process by preventing fusion of the autophagosome with the lysosome, allowing accumulation in the cytosol. Murine MC38 colorectal adenocarcinoma tumor cells were cultured and treated with 200 μM chloroquine for four hours. Immunofluorescence staining was done for LC3-II (green), actin (phalloidin; red) and nuclei (DAPI; blue). Chloroquine increased LC3-II puncta in both the MC38 tumor as well as the murine pancreatic adenocarcinoma Panc02 cells (not shown). For details, see article by Liang and colleagues on page 2791 of this issue.