Anti–4-1BBL and anti-CD70 do not inhibit the anti-CD40–induced expansion of splenic DCs or the effector stage of the response in vivo. (A) Mice received BCL₁ cells, anti-CD40, and anti–4-1BBL and anti-CD70 as described in Figure 1B. The total number of DCs recovered from each spleen after collagenase digestion was determined by flow cytometry using PE–anti-CD11c. Data points are the mean of 2 mice, and results are 1 of 2 similar experiments. (B-C) Mice received 2 × 10⁷ BCL₁ cells intraperitoneally on day 0 and then anti-CD40 mAb (1 mg) on day 1. On day 8, 1 mg of the appropriate blocking mAb was given intraperitoneally and then 5 hours later 2 × 10⁷ CFSE-labeled splenocytes from BCL₁ tumor-bearing mice (> 70% BCL₁ tumor). Peritoneal cavity cells were harvested 24 hours later, stained with PE-labeled anti-BCL₁ Id, and evaluated by flow cytometry. (B) CFSE⁺/Id⁺ cells surviving as a percentage of total CFSE⁺ cells are shown. Error bars represent mean × SD for 3 mice; rechallenged, and rechallenged + anti-CD4, anti-CD70, and anti–4-1BBL groups were significantly different from naive, P < .005; rechallenged + anti-CD8 was not significantly different from naive. (C) Representative dot plots are shown. The double positive (CFSE⁺ and Id⁺) cells (R1) represent the surviving tumor cells.