Effect of the treatment with anti-Sn MoAbs in vivo on the efficiency of ADI therapy in tumor-bearing DBA/2 mice. (A) Tumor-bearing mice (6 animals per experimental group) were treated IV with the mixture of anti-Sn MoAbs (1C2 and SER-4 directed against different epitopes of Sn) 1 and 3 days after ADI. (▪) Control (nontreated tumor-bearing mice); (□) ADI-treated tumor-bearing mice; (▴) tumor-bearing mice injected with anti-Sn MoAbs 1 and 3 days after ADI; (•) tumor-bearing mice injected with normal rat IgG (control Abs). One representative experiment of three is shown. (B and C) Immunohistochemical pictures of frozen liver sections from tumor-bearing DBA/2 mice (at day 8 after ADI) treated with immune cells only (B) or in combination with the mixture of anti-Sn MoAbs (1C2 and SER-4) (C). Shown are periportal areas in which most of the Sn⁺ macrophages are located. (B) shows the staining for Sn (pink) and (C) shows the staining for anti-Sn MoAbs (pink) using goat antirat second antibody (original magnification × 200). pv, portal vein. (D) Presence of CD8 T lymphocytes in the livers of mice treated with ADI and anti-Sn MoAbs. Total number of CD8 T cells in ADI-treated mice (▪) and in animals injected with anti-Sn MoAbs 1 and 3 days after ADI (□). Number of CD8 T cells associated with Sn⁺ Kupffer cells in clusters in mice treated with ADI only () or with ADI in combination with anti-Sn MoAbs (▧). Data represent the means and standard deviations from two experiments with 2 to 3 animals per time point. *Statistically significant difference when compared with the respective control.