Anti–mouse CD16/32 (FcR) mAb (2.4G2), anti–mouse CD11b mAb (5C6), control hamster Ig (UC8-1B9), anti–mouse CD4 mAb (GK1.5), anti–mouse CD8 mAb (53-6.7), anti–mouse FasL mAb (MFL3), and anti–mouse TRAIL mAb (N2B2) were prepared in our laboratory as previously described (4 (link), 19 (link)). Biotinylated anti–mouse F4/80 mAb (A3-1) was purchased from Caltag, biotinylated anti–mouse CD205 mAb (NLDC-145) was purchased from Cedarlane Laboratories, and biotinylated rat IgG2aκ (R35-95) and rat IgG 2bκ (A95-1) were purchased from BD Biosciences. A hamster IgG2 anti–mouse DR5 mAb (MD5-1) was generated by immunizing an Armenian hamster with mouse DR5-Ig fusion protein (DakoCytomation), fusing the splenocytes with P3U1 mouse myeloma cells, and then screening the reactivity to mouse DR5-transfected BHK (BHK-mDR5) cells by flow cytometry. MD5-1 was purified from ascites using a protein G column. Biotinylation was performed as previously described (20 (link)). Requests for MD5-1 should be addressed to H. Yagita (hyagita@med.juntendo.ac.jp).