Effect of host liver macrophage depletion in vivo on the efficiency of ADI therapy in tumor-bearing DBA/2 mice. To generate antitumor immune effector cells, ESb-MP lymphoma cells were inoculated IV at a dose of 10⁵ cells into B10.D2 mice. One week later, spleen cells were isolated and transferred IV into sublethally irradiated ESb-MP tumor-bearing DBA/2 hosts (ADI, d0). Kupffer cells were depleted from the host by IV injection of Cl₂MBP-liposomes. Each experimental group contained 10 mice. Chlodronate entrapped in liposomes did not induce any toxicity both in normal mice and in ESb-MP tumor-bearing animals (data not shown). (▪) Control (nontreated tumor-bearing mice); (□) ADI-treated tumor-bearing mice; (•) tumor-bearing mice injected with Cl₂MBP-liposomes 2 days before ADI; (○) tumor-bearing mice injected twice with Cl₂MBP-liposomes 2 days before and 4 days after ADI. One representative experiment of three is shown.